In the North Sea, the crew of the Kinloch Bravo oil rig is getting ready to finally
go home after months of hard work.
Unfortunately Magnus, the rig manager, is receiving a call from the company with bad
news.
The helicopters are diverting to help the North Kilscour platform with its power failure,
so they don't know when they'll be able to pick Magnus' crew up.
Magnus wants to ask for more details, but the phone suddenly stops working.
Communications start falling all over the building: Cat's call with her wife freezes,
and Fulmer can't make the main radio work either.
Magnus calls for a meeting and announces that they'll have to wait a while to go home.
This isn't well received by anyone, especially not by Lars, who keeps asking for proper explanations.
Suddenly, the power goes out in the whole building, and Fulmer discovers all generators
are down.
The battery backup is holding things up for now, and the Production Module's holding its
pressure, but if it spikes it could kill them all.
Fulmer tries to get in contact with the stand-by vessel, but the radio still isn't working,
and the other oil platform near them seems to be having the same trouble.
The whole rig begins shaking and the Production Module is starting to catch on fire getting
out of control.
Rose, the company representative, doesn't want to shut it down yet because they'll be
way off quota, but Magnus orders his men to shut down the module anyway for the sake of
their lives.
At that moment, the whole rig begins shaking again.
Everyone stares in shock when they notice a very thick and fast fog enshrouding the
entire building.
Moments later, Fulmer manages to bring power back, but communications are still off, and
there's no way the choppers will come in this weather.
Alwyn wonders if they haven't drilled too much and caused a seismic event, but Rose
is a scientist and assures him it doesn't work that way.
Magnus thinks fixing communications is their priority, so he sends Fulmer and Baz to check
on the radio tower.
When they make it to the top, Fulmer begins checking the machine, but he loses his temper
when Baz accuses him of betraying the team for getting into a relationship with Rose,
who is on the company's side and not theirs.
Baz quickly apologizes, and when Fulmer lets go of him, he moves to pick something up and
finds a dead seagull on the floor.
Magnus and Lars are waiting at the base of the tower when suddenly they see Baz fall.
Cat and Rose rush to the scene with a medical kit while Fulmer comes down as well, explaining
he doesn't know what happened because Baz had been right behind him.
Lars doesn't trust his story because he notices Baz's harness was unclipped.
Cat takes Bax to the medical bay and stabilizes him, but there's nothing else she can do without
a surgery room.
Lars starts losing it because there's no way choppers will come in time.
Rose brings Magnus to the computer to show him that the pipelines have no pressure, which
means all the rigs in the area are having the same trouble as them.
Moments later, Baz wakes up and begins having visions of things coming apart under the sea.
Lars goes to Magnus' office to blame him for everything, but Magnus ignores the complaints
and leaves.
This allows Lars to snoop around his desk and found a private memo from the company
that makes him furious.
He gathers everyone on the helideck to inform them management has been lying to them from
the start.
Magnus comes over too and sees Lars has the memo, so he has to confess that the company's
junking the whole field and everyone will lose their jobs soon.
The conversation's suddenly interrupted by something falling on them: it's ash, even
though they aren't anywhere near a volcano.
Baz shows up at the helideck as well and announces that "it's too late, it's already started"
before passing out.
Later, Baz wakes up in the infirmary and explains he doesn't remember the accident or the helideck.
At the tower, he saw something in the fog and heard a noise in his head.
Baz reacts violently when Cat tries to take blood, and yells at them for not listening
to his warnings because there's a wave coming.
After Cat manages to put him to sleep, she explains to Rose that Baz's wounds are somehow
quickly healing on their own.
Once the women are gone, Baz reveals he's still awake and when he checks his injuries,
he sees some glowing spores working on closing them.
In the rec room, the crew notices some lights by the window: it's the stand-by vessel, which
is trying to communicate but also going in the wrong direction.
Alwyn sends Leck outside to get the morse message, and they discover the vessel's asking
for help.
Magnus orders Fulmer to sign back to them using the deck lights to find out what they
know, then he goes to see cook Murch to ask him to start rationing their food.
Lars is starting to go crazy because he was locked up in his room with Easter guarding
the door.
In the infirmary, Baz wakes up again to notice most of his injuries are healed, and when
he checks his reflection, he begins having a vision of the rig being destroyed.
Then he escapes to his room and while getting dressed, he begins wriggling in pain as his
mouth pushes out his gold tooth.
Rose gathers some ash to analyze it and orders everyone to stay inside.
Fulmer informs her and Magnus that the vessel doesn't have more information than they do.
They don't have communications either, so if they wait for morning to come, they won't
be able to use the lights to guide them in and the boat could crash.
If they evacuate it should be now, but Rose doesn't want to because it could get them
in legal trouble for breaking the contract, but Magnus' priority is everyone's safety
and he asks Fulmer to keep up the lights to guide the vessel slowly.
Alwyn goes outside to take over Leck's shift and finds Baz drawing weird circles on a window.
When he checks on him, Baz explains his head is full of noise and that he shouldn't have
survived the accident, something is definitely not normal about this situation.
The lights in the room start flickering and Baz has another weird vision before running
away.
Lars starts working on the window and manages to take it off the wall to escape.
Leck sneaks into the infirmary to steal the rubbing alcohol to get drunk, then tries to
have a shower.
At that moment his body begins hurting all over and as Leck throws up blood, the ink
of his tattoos starts to come off his skin.
By the time Heather finds him, he's already dead.
When Cat comes to check on him, she can't tell what killed him, but when Dunlin shows
up with Baz's tooth, she's sure there's something pushing inorganic material out of their bodies.
In the control room, Fulmer notices a light on the bridge that doesn't come from the vessel.
He and Alwyn go outside to check it out, but Lars sees them and turns off his flashlight
before they can catch him.
He sneaks back inside the building through the door they used and locks it, bumping into
Heather on the way.
Fulmer and Alwyn check the row boats in case anyone is trying to escape, and Fulmer accidentally
wounds his hand.
At that moment, the ash mysteriously stops falling.
Lars goes to the control room and starts signaling SOS with the lights, causing the vessel to
come at full speed.
Alwyn and Fulmer see the message and try to get back inside but the door's locked, so
Alwyn goes looking for another entrance while Fulmer keeps on shouting.
Heather hears him and brings Magnus to help her open the door.
Fulmer tells them about Lars and they rush to stop him, almost starting a fistfight before
Magnus asks them to concentrate on sending a message to the vessel to correct its course.
Alwyn's currently following some lights flickering that lead him to Baz, who refuses to come
back because he needs to see "the life in the water that started it all".
Alwyn insists and makes Baz snap, grabbing Alwyn and making him spout water through his
mouth.
Dunlin arrives to warn them about an incoming wave caused by the boat changing course, so
Baz drops Alwyn and runs away.
Dunlin drags Alwyn's body away from the water and Magnus comes to help with CPR, but it's
too late.
When Cat arrives she confirms Alwyn somehow drowned.
Rose continues to study the ash and when she drops a bit of blood on it, she confirms there
are living organisms in it.
She goes to see Magnus, who informs her the vessel left to help another rig first.
Rose brings him and Cat to her office to explain the ash has some kind of parasitic spore that
is looking for hosts and it repairs their wounds quickly because it wants a healthy
body.
They have to avoid long exposure to the ash and keep an eye on people with open wounds.
Magnus authorizes Rose to take blood samples from the whole crew to compare them to what
they have from Baz.
In the mess hall, Heather notices the fog is finally going away and the neighboring
rig has completely been destroyed.
Fulmer finds Baz looking at Rose's research and tries to offer help, but Baz refuses because
the light needs him.
Rose arrives too and sees Baz has taken his own blood sample, so when she asks for his
cooperation, he runs away.
When Magnus hears about what happened, he sends Cat to check on everyone that has injuries
since they can't do the testing anymore.
After isolating Fulmer, Magnus calls for another meeting.
Now the fog and ash are gone, he wants half the team to disinfect the rig thoroughly,
and the other half must find Baz.
Rose continues investigating and discovers the spores have been seen before fossilized
in layers of Earth.
They should've died with the dinosaurs, but drilling so deep has awoken a sleeping nest.
Outside, Baz is throwing his blood sample into the sea.
His body is fully healed now, and he touches the tanks of water as a test, instantly filling
them with spores.
He hides when he hears James looking for him, but when James sees the spored water and calls
for help, so Baz has to shut him up.
Lars and Dunlin come to the room and find James wounded on the floor.
Lars notices the spores in the water have started to grow plants.
In the machinery room, Heather, Easter, and Murch also find plants growing on the oil.
Suddenly the rig starts shaking again and Dunlin realizes James is bleeding.
When the boy opens his hand, he reveals he lost a tooth, meaning he's infected.
Scared, James hits Dunlin and runs away.
The rig starts losing power again, so Magnus takes Fulmer out of isolation to make him
fix it.
Heather sees Baz and follows him into the mud pit, where Baz is growing plants all over
the place.
Baz explains a million-year-old memory has told him he needs to defend this place because
it's being attacked, if it dies everyone will go down with it.
Suddenly James shows up too because he's joined Baz's cause.
The rest of the team realizes Heather's gone and Lars comes to rescue her, making Baz and
James run away before Heather can get more answers.
Fulmer manages to restore power and the team discovers the flare on the Production Module
is gone.
They need to disconnect it from the electricity system to stop it from exploding, but the
module control is in the mud pit where they could be infected by the spores.
Their only option's to reignite the flare manually, and Fulmer accepts to take the risk.
Easter controls the crane to bring Fulmer closer to the module, but it's not enough,
thus Fulmer unclips his harness and comes as close as possible for a proper shot.
The flare is turned on again successfully, but Fulmer's hit by the fire and has to be
taken to the infirmary to take care of some serious burns on his back.
In the mud pit, Baz's visions get worse and he comes to the conclusion they need to shut
down the rig's system to stop "the attack".
James tries to close the valve, but the pipes are still pressured and they could blow up,
so they're going to access the system from the source.
Later, after a visit from Rose, Fulmer swears he feels fine and gets dressed because he
wants to help.
He, Rose, and Heather begin working together on the research, and Fulmer unconsciously
draws some circles on a pad like Baz used to.
Suddenly Magnus calls them all to the control room, where he's discovered the pressure is
incredibly high because Baz is trying to bypass the safeties for the well.
Fulmer can't take control away from him remotely, so they will have to take a risk with the
bullseye ROV.
Easter guides the ROV and gets underwater images showing that the earthquakes have created
a series of circles on the land that remind Fulmer of his drawings.
The ROV carefully approaches the wellhead and shuts it off, making Baz furious because
his plan has failed.
He tries to access the system directly from the CPU but it has an alarm on it, so they
need Fulmer to disable it.
Suddenly, Easter's phone gets a message, and the crew discovers communications are back.
Magnus tries to contact the coast guarda and Fulmer googles the meaning behind circles
that seem to be communicating something.
Rose searches the company's system for some containers Heather found and nobody knew about,
only to discover a project called "Cirein" that she can't access.
She also finds Fulmer's drawings.
Cat calls her wife, who explains the company told the families the crew's fine and that
they've also been having electrical problems.
At that moment, the fog arrives in the city, and now people on land are the ones without
power.
Internet signal goes down, and the guard doesn't get Magnus' messages asking for help.
Baz uses his spores powers to connect with Fulmer's body, which begins healing more quickly.
Fulmer also begins hearing Baz's voice in his head, so he runs to the bathroom to look
at his wounds.
Rose sees he's missing and goes to check on him, startling Fulmer because for a moment
he sees Baz in the mirror.
He confesses everything to Rose, who kisses him to comfort him.
This causes Fulmer to have a vision of her suffering and Baz's apparition asking him
to join him.
Hours later, Rose checks on Fulmer again, only to find a note he left behind.
Rosa goes after him and Cat joins her, together they find Fulmer going to the mud pit.
The girls enter the pit too and the spores approach Cat but don't attack, instead they
circle her stomach because they're curious about the baby.
Rose drags Cat out before it gets worse, and they find the crew getting excited because
there's a series of lights approaching the rig.
It's a ship coming from the neighboring rig.
The crew receives the survivors and Rose meets Coake, who works for the company's research
division and demands to be taken to the control room immediately.
Cat checks on the other men to make sure there aren't any injuries and Easter's surprised
to see his old flame Harish among them.
Coake explains his rig exploded after a pressure failure and thinks they need to prioritize
getting access back to the production module.
Rose wants to know why Coake had been sent to the rig, but he refuses to explain.
In the infirmary, Harish tells Easter a different story.
When Coake arrived at the rig, he sent a bunch of people home and the rest had to help him
install some new equipment.
They weren't drawing oil up from the well, they were sending something down.
Then the fog came in and people started to disappear, but Coake stayed calm as if he
had done this before.
He kept pushing the equipment test and ignoring the pressure warnings until the rig exploded.
Heather enters the system to crosscheck the list of survivors with the crew files, but
she can't find Coake's name.
She tells Easter and Harish about this, and Harish explains Coake had been accessing the
system with a temporary account the IT guy made when he arrived.
Before they left the rig, he wiped everything related to the test.
Heather checks the system and Harish points at a strange name on the crew list that wasn't
there before.
There are e-mails telling the company that the organism has already spread, which means
Coake's always known and the company sent him on purpose.
Cat checks on Rose and thinks the circles she's studying look like a tree, making Rose
realize this may be how the spores keep track of time.
The gap between the rings marks the five major mass extinction events, which means the last
ring is the present and is closing up quickly to destroy them.
Coake explains that's what happened in his rig, the explosion had been caused by the
infected people opening the well to blow it up.
He wants to send a team to the production module, but Magnus refuses to take that risk,
and Rose guesses all those containers and the testing are the secret Project Cirein.
Fulmer finally joins Baz and James, but he notices his mind is clearer than his friends'.
Baz explains he hasn't been exposed to the spores long enough yet, but they'll take over
soon.
Baz can help him harness them if Fulmer accepts to deal with the system.
Fulmer begins to work but it'll take a while to shut down the alarm.
Dunlin, Lars, and Murch call Coake for a private meeting because they're sick of Magnus' bad
decisions and want to hear Coake's ideas.
Coake explains they can stop Baz by using the carbon dioxide from the secret containers
to knock him down, it's just a matter of entering the mud pit and connecting the carbon dioxide
to the ventilation system.
The trio gets the canisters from the containers and Dunlin gets suspicious because the label
says the carbon dioxide's mixed with something else.
They take the canisters to the mud pit and connect them to the ventilation shafts, protecting
themselves with masks.
Baz sends James and Fulmer to check what's going on and James finds the trio first, only
to suddenly throw up blood on them.
The guys realize the carbon dioxide isn't knocking James out, it's killing him and the
plants because that was Coake's plan all along.
Lars and Murch run away, but Dunlin doesn't join them until he's sure James can't be saved.
Fulmer tries to shut off the ventilation but both he and Baz pass out.
In the control room, Cat finds Coake shutting down the doors around the mud pit after Lars
and Murch escape, trapping Dunlin inside.
Dunlin's mask runs out of oxygen and he dies too.
Heather and Harish tell Rose and Magnus about Coake and go to confront him, but Coake defends
his actions as survival.
Magnus opens the doors but he can't get access to the ventilation pits, so Rose goes down
there and takes a mask from Lars to enter the mud pit.
She shuts down the ventilation manually and then checks on Fulmer, who doesn't wake up
when Rose shares the mask.
However when she accidentally touches the plants, the spores react and bring Fulmer
back to consciousness.
They escape the pit together while Baz also wakes up and the last ring closes underwater.
Magnus meets with Harish to hear the real story: Coaked pushed the testing to the limit
because he wanted to destroy the spore, losing the rig was just collateral damage to survive.
The vessel came to rescue them but it crashed, so they wiped the system and got away on a
small lifeboat, meaning they left people behind to die.
Afterward, Magnus interrogates Coake, who explains this has all been company policy.
They don't want to lose their precious oil reserves, they just want to keep drilling
without interruptions, thus Coake was sent to exterminate the spore.
If they don't stop it now, it'll spread all over the world.
In order to survive, they need to kill every infected person.
Magnus discusses their options with Rose, who thinks killing the infected ones won't
do anything so she'll work with Fulmer to find an alternative.
Perhaps Fulmer can communicate with the spore like Baz does and explain they could cooperate
instead of attacking each other.
In the pit, Baz senses the spore is shutting him out, and another earthquake hits the rig.
Fulmer uses a little plant to connect to Baz and sees the spores are trying to trigger
the next great slide to wipe the ocean clean.
Rose points out that the spore's a living network threaded throughout the sea floor
all over the world, so attacking it here will barely hurt it.
She thinks they should talk to Baz and make it stop the spore through his bond.
Magnus would rather team up with Coake to stop it, but the others support Rose's theory
and Magnus gives them permission to try.
Magnus, Rose, and Fulmer enter the pit, where Magnus keeps having visions of his dead son.
They find Baz crying in a cloud of spore, saying it's too late and that he failed.
Coake looks for Harish, explaining there are choppers already coming and that he'll bring
Harish and his boyfriend if he helps him finish his mission.
Harish suspects Coake wants to make the rig explode to cover it all up and he secretly
activates the microphones before making Coake admit everything for everyone to hear through
the speakers.
The earthquakes begin getting worse and the whole building begins breaking.
Coake hits Harish to get him out of the way and start the explosion countdown, that's
the moment when the choppers finally make contact with them.
Coake runs away to the helideck to escape alone, and Cat and Heather go after him while
Easter helps Harish stop the imminent explosion.
At the helideck, Coake finds Lars waiting for him with the intention to kill him for
revenge, but the girls arrive just in time to stop him.
Harish shows up to announce he stopped the explosion, so now everyone needs to get ready
to evacuate, and Lars punches Coake before joining the crew.
In the pit, Rose notices the spore behaving differently, so she touches it.
She manages to communicate with the spore but before she can ask it to cooperate with
humanity, the rig is hit by the worst earthquake yet and the guys drag her out.
Baz decides to stay behind to prove to the spore that humans are capable of giving too.
Magnus, Rose, and Fulmer catch the last helicopter, and they fly away right before a tsunami hits
the rig, bringing it down at the same time Baz becomes one with the spore.
Cat notices the tsunami will hit the beach and wants to warn the citizens, but the pilots
push her away as Coake explains they aren't going home.
At that moment, the tsunami hits the city and kills Cat's wife.