In the late 1970s, a scientist drags her body through the jungles of Zaire. She's been trying
to study and understand a plant known as Triffid, which is quite dangerous. The woman can't escape
their fury and dies in the jungle, but she manages to warn her son so he can get away. Thirty years
later in 2009, the Triffids are being kept in labs away from cities to be used for their oil,
which is an alternative to fossil fuel and has put an end to global warming. Oil companies
are keeping citizens in the dark about this because of how dangerous these plants are,
not only because they can feed on people, but also because they have venomous branches that
can blind a person. All labs keep extra security measures not to leave any Triffid unattended,
and when scientists have to come closer for studies, they wear eye protection and come
with a guard that keeps the vines back with tasers. One of these many scientists is Bill,
the son of the woman that died in the jungle. He wants to finish his mother's work because he also
believes Triffids are smarter than they look and the noises they make are actually communication,
so he keeps plenty of recordings of them. He also suffers from constant nightmares that showed him
blurry memories of the night his mother died and included weird images of natives from the jungle
approaching him with a mask. One afternoon, while Bill is making more recordings under guard Lucy's
protection, they discover that an anti-Triffid activist Walter has sneaked inside the lab because
he wants to reveal the truth to the whole world. Walter knocks Lucy out by surprising her from
behind and makes her lose her goggles, so Bill comes closer to give her his own. He also uses
the chance to take her taser and stun Walter, but the sudden movement gets the Triffids' attention
and Bill ends up with venom on his eyes. As the other guards finally arrive to arrest Walter,
Lucy grabs Bill and drags him to the local hospital, where the doctor gives him an anti-venom
after bandaging Bill's eyes. He has a 50-50 chance to become blind, but they need to wait twenty-four
hours to be sure. Meanwhile people around the world are getting ready to watch a meteor shower.
Radio reporter Jo interviews an astrophysicist who explains the sun will release a vast explosion of
gas and nuclear fire that will look like fireworks in the sky, but it can't cause any damage to
humans. However when the show finally starts a few hours later, the solar eruption flashes such
a bright light all over the world that causes all technology to lose signal and the people watching
to feel a burning sensation in their eyes. Because Bill spends the night sleeping with his
eyes bandaged, he has no idea of what's going on. When he wakes up a few hours later, he goes to the
bathroom and removes the bandages to discover his eyes are just fine, but after leaving his room, he
also discovers everyone around him is panicking. He looks for the doctor and finally learns what
happened from him: the solar eruption left most of the population blind. Bill decides to quickly
leave to go back to the labs, afraid of what is happening to the plants without supervision,
and finds the city has succumbed to utter chaos. In the Triffid labs, Walter notices the lights
in the sky being stronger than they should be, and he covers his face with his hood to protect
his face. Everyone else in the lab including Lucy loses their eyesight, so Walter takes
advantage of this to escape his cell and free the Triffids. In a plane that is flying over the city,
Torrance doesn't care about the meteor shower and is sleeping through it with an eye mask on,
meaning he doesn't wake up until he hears everyone panicking. The plane's going down because the
pilots can't see either, but Torrance ignores all the cries for help and hides in the bathroom with
a bunch of life jackets. When the plane crashes, Torrance's the only survivor and he immediately
begins taking advantage of the chaos in the city to rob stores. Meanwhile Jo wakes up with her
eyesight intact because she's been underground in a subway station, which is now in ruins because of
the plane crash. When she goes outside, she bumps into a mother with a kid and they realize she can
see, so they begin begging for her help. Soon lots of people are surrounding Jo, trying to drag her
away for their own protection, prompting Jo to get in a car and try to drive away. Unfortunately the
street is blocked by the blind crowd, allowing a cop to approach Jo and try to arrest her under
some flimsy excuse to take her way. At that moment, Bill shows up looking for an authority
figure and notices what's going on, so he takes advantage of the cop's blindness to take the
gun from him and rescue Jo, then the two of them run away by keeping quiet in order for the blind
people not to notice them. After walking for many hours, Jo and Bill manage to reach Whitehall, but
a crowd of blind people is blocking the entrance. They go through it to try to reach the guards,
but communicating with them is useless because they only answer with shots. With no authority to
talk to for help, Bill decides to go to the labs himself, and Jo goes with him not to be alone.
The pair steals a car to reach the lab, where they discover the Triffids have escaped and everyone is
dead, including Lucy and Walter. Bill retrieves all his research because he thinks it may come
in handy later, then he accepts to take Jo to her father's house so she can check on him. Sadly by
the time they make it there it's too late: the man is already dead and being taken away by the
Triffids. Jo refuses to believe it and tries to shoot the plant, but this only makes the Triffid
angrier and Bill has to drag Jo away before they get surrounded. Now that Jo has seen how dangerous
these plants can be, she decides she wants to warn people, so the pair returns to London to
use the emergency broadcast from the BBC. Jo has a quick interview with Bill to finally let the
world know about the Triffids, warning them that they'll be searching for food and that means these
plants will most likely be coming to the cities. Afterward, they take a break to eat something,
and Bill tells Jo about his childhood. His father Dr. Masen was the one that discovered
that genetically modifying the Triffids could give them the solution to the energy crisis,
but his mother hadn't agreed with his work. She obviously died that day in the jungle,
but Bill hasn't seen his father since. Meanwhile Torrance sneaks into the prime minister's home
only to find his now-blind secretary Hilda. He spends the night there, and in the morning,
Hilda plays for Torrance the emergency broadcast, which confirms there aren't any authorities left.
Torrance wants to take advantage of this to take power for himself, and he leaves while
dragging Hilda with him. Sometime later, Bill sees flares signals coming from across the city,
which must indicate a group of people that can see must've formed a community and is letting others
know where to find them. On their way there, they come across Torrance, who is taking weapons from a
military van that was attacked by a Triffid. He offers to team up because supposedly he's alone
when actually Hilda is in the car, but Jo and Bill turn him down. Moments later, they make it to the
building that sent the flares and discover they don't allow blind people to enter. Jo and Bill
are allowed inside and received by some employees of the Home Office, who explain they have their
own generator here. Bill warns them about the Triffids, but since the plants are easy to avoid
if you can see, the community leaders would rather concentrate on gathering supplies and finding
a place where they can escape to. They have no intention of bringing the blind with them because
they can't be taken care of, which Jo considers to be completely immoral and makes her not want to
work with them. Bill's trying to leave to find his father and work on a way to stop the Triffids, but
he isn't sure it's a good idea for Jo to come with him. In the meantime, Major Coker is leading a
group of sighted people to help the blind that are being ignored by Home Office. Torrance finds them
and joins the group pretending he wants to help too, buying his way in by sharing all the weapons
he's gathered. Coker and his men don't waste time and enter the building through the parking lot,
knocking everyone out with tear gas and smoke grenades. Everyone that can see is taken away,
including Bill and Jo. Moments later, Coker handcuffs every sighted person to a blind one
for survival, Bill ends up with an old mechanic and Jo ends up with Hilda. Bill thinks Coker's
heart is in the right place, but it was dumb of him to ignore the Triffid threat just because
they're armed. Next, the group is taken to London to search for supplies. The first few houses they
search are empty, and when they stop to take a break, Torrence lies and tells Jo that Coker would
love for her to start a new broadcast to gather people for their cause, but she turns him down,
not approving of these methods. Afterward, the group finds a supermarket warehouse with plenty of
food for them to take. It's easy for them to get inside but that's because the guards are already
dead: the Triffids got there first. Jo is grabbed by one of them, and Bill manages to save her by
using a lighter and a spray to light the plant on fire. Unfortunately they still lose a few people
in the other corridors, including Hilda, because the guard Torrence had assigned runs away like a
coward. Coker finally takes the Triffids seriously and uncuffs the people left, thus when Torrence
arrives, Coker demands to have more weapons to fight the Triffids and Bill as his right hand.
Torrence obviously doesn't like it, but for now he accepts to play along. When they return to London,
Jo sees Coker's change of mind and accepts to do a broadcast to help before she leaves with Bill to
look for his father. Torrence doesn't want her to leave, so he asks her to do a broadcast right now
without any planning, and immediately people all over the city come to them to join their cause.
While Jo is busy, Torrence sends his men to kidnap Bill and Coker and take them to the forest to make
it look like they were attacked by Triffids while Torrence takes over the leadership of
the group. After the broadcast is over, Torrence tells Jo that Bill died during an attack, giving
her the things his men took from Bill's jacket as proof of his story. Meanwhile in the forest,
Torrence's men make noise to get the Triffids' attention, but the plants get to them faster than
expected and kill them all. With the Triffids busy attacking the soldiers, Bill and Coker get
to escape and gain control of the truck, although Coker's eyes get sprayed with venom on their way
out and Bill loses his tape recorder when he uses it to distract the Triffids with their own noises.
When eventually the truck runs out of gas, the pair begins looking for shelter on foot. The next
day in London, Jo continues to make broadcasts to call people over from all over the country,
and Torrence asks Jo out for dinner, saying they still need a happy moment in dark times,
but Jo turns him down. Later, Jo notices people are building a wall around the area to keep the
Triffids out and is starting to get suspicious of how much attention everyone pays to Torrence's
orders when this should be Coker's operation. Since Coker hasn't been around for a while,
Jo approaches a young fighter named Troy to ask if Bill really is dead, and Troy admits they
don't have proof, just the tape recorder one of their men brought back from the forest. Furious,
Jo sneaks into Torrence's office and recovers the recorder to put it safely away with the
other Bill's things. Back to Bill and Coker, they finally come across a church where a religious
group takes them in and helps them with their wounds. This group is led by Mother Durrant,
who doesn't turn any refugees down and explains that the building is safe from Triffids. Bill
finds this suspicious because it doesn't fit Triffid behavior, but Durrant promises this is the
protection of God. Coker decides to stay with this community but Bill leaves the church to continue
looking for his father. As soon as he enters the forest behind the church though, he finds
out the truth behind the so-called protection: it turns out Durrant has been sending people,
even priests and nuns, as food for the plants to eat and keep them from attacking the church. Bill
immediately goes back and arrives just in time before Durrant sends another girl away under
the excuse she was chosen to build a new community somewhere else. As soon as Bill tells everyone the
truth, the community kicks Durrant out and accepts Coker as their new leader, now Bill can leave for
his father's place without worrying about them. In London, Jo tells Torrence she does want to go
to dinner with him, pretending to be on his side. Later in the evening, while Torrence is getting
ready for the date, Jo makes one last broadcast telling people not to come because Torrence will
want them to die for him. Obviously this angers Torrence and makes him send his men after her,
but Jo is already on the run with all of Bill's things in her pocket. Troy does see her hiding,
but instead of snitching, he lets her get away. It's quite difficult to run through the city
while dodging all the Triffids, but eventually Jo manages to find a working car and drive out
of London safely. She remembers the place Bill grew up in from when he shared his story and
takes the car in that direction, only to end up accidentally crashing and having to continue on
foot. When she enters the forest, a truck shows up ahead of her, and no matter how fast she runs,
the driver comes after her and captures her. In the meantime, Bill arrives at a town that
has been abandoned after a Triffid attack. He almost gets shot by the only two survivors,
who turn out to be two very young sisters called Susan and Imogen. Susan is very wary of him, but
Imogen is desperate for the company of an adult and accepts to give Bill the family car as long as
he accepts to take them with him. After driving a couple of hours, they come across another vehicle
and the driver turns out to be Bill's father Dr. Masen. The reunion's far from warm, but
Dr. Masen doesn't hesitate to bring Bill and the girls with him to his house, which is fenced with
electrocuted wires. Inside Bill finds Jo, because it had been Dr. Masen who found her in the woods.
After Jo gives Bill back all his things, the two of them finally kiss and spend the night together.
Sometime later, Bill joins his father at the lab, where he's already preparing a new plan. He thinks
that to stop the Triffids, they must create a new type of it that sterilizes instead of fertilizes.
If they spread this new type of Triffid around, then they'll make all the others infertile and
eventually the race will die out. Dr. Masen already has a female Triffid he's been working on,
but to finish the experiment, he needs the pollen from a male Triffid, so Bill promises to find one.
Meanwhile Susan and Imogen are practicing target shooting and Susan gets incredibly frustrated with
Imogen because she's already referring to Jo and Bill as "mom and dad". Once he's properly armed,
Bill drives all the way to the labs to see if at least there's one male Triffid in the area. Once
again, he uses his tape recorder to play Triffid noises, but the first one to show up is Susan,
who hid in the car and came along to keep an eye on him. While Bill scolds her for such a dangerous
idea, a male Triffid finally shows up and grabs Susan, making it hard for Bill to shoot at it
properly if he doesn't want to hit the girl too. In the end, he decides to jump on the Triffid and
hit it until it dies. Bill and Susan bring the Triffid head back to the house and Dr. Masen
immediately begins working on it while discussing his wife's old ideas. After Bill goes through
those awful flashbacks again, Dr. Masen reveals he still has some of the things that used to belong
to his wife, including her own recordings and a creepy black mask that matches Bill's flashbacks.
That night, Triffids all over the country begin sporing, thus Torrence sends Troy to the lab to
find Bill's file in order to find him and a solution to this problem. The next morning,
a helicopter flies above the house and drops a bunch of pamphlets promoting a survivor's colony
in the Isle of Wight, and the new family agrees to go there after they're done with the experiment.
Dr. Masen decides to listen to his wife's old recordings to try to figure them out while feeding
the Triffid, but this proves to be a mistake: the noises make the plant extra violent and it
attacks the doctor through the door hatch. Bill hears all the screaming and rushes to the lab,
where he turns off the tape before shooting the plant. Unfortunately it's too late: Dr. Masen
had been stung already and he dies of the venom. After giving Dr. Masen the goodbye he deserves,
Bill realizes he destroyed the mutated female and there's no time for him to restart the experiment
from scratch, so the family agrees to leave for the island in the morning. Things don't go as
planned though because as soon as the sun rises, Torrance shows up with his men and captures the
sisters, threatening to kill them if Bill doesn't come up with a solution to deal with the Triffids
in 24hs. The family is locked up together, but no matter how much Bill thinks, there's no solution
to the experiment, thus their priority must be to escape. His idea is to use the recordings to
attract the Triffids and sneak out of the house while the plants attack Torrence's men. At that
moment, Bill is called to see Torrence, so he gives Susan the tape recorder to hide. While
Torrence taunts Bill and cruelly teases him for losing his parents, Susan climbs out of the window
and leaves the recorder outside playing. When night falls, the Triffids arrive at the area,
approaching the house easily because the wired fence had been turned off by Torrence. Furious
about this turn of events, Torrence goes outside with his men to start shooting at the plants, but
he also sends Troy to kill the family as revenge. However when Troy makes it to the room, he can't
bring himself to do it, and he shoots the air to trick Torrence into thinking the family is truly
dead. Then, Troy knocks out the guy in charge of the house power switches, and when Torrence sees
the plants are close enough for electrocution, he sends an order through the walkie-talkie asking
for the electricity on the fence to be turned on. Troy pretends the switchers don't work and the
Triffids get to attack the men. Torrence leaves his followers to die and runs back into the house,
where he finds Troy escaping with the family and shoots him in the leg. Bill retaliates by
tasing Torrence and knocking him out, but this delay has given time to the Triffids to surround
the house and block all the exits. Hearing all the men dying triggers Bill's flashbacks and
he finally remembers what the mask is for: if you pour venom into your eyes while wearing the mask,
the liquid won't hurt you but it will make the plants think you're one of them. They had done
that to him as a kid and that's why he got to escape while his mother couldn't. Using a
Triffid branch that got broken during the fight, Bill puts the whole group through the process,
and when they go outside they confirm it works: none of the plants dares to attack them. At
that moment, Torrence wakes up and tries to go after them, but as soon as he comes out,
the Triffids jump on him to eat him while Bill and the others run away. Sometime later, Bill, Jo,
Troy, and the sisters are on a boat, making their way to the island of survivors and hoping to find
enough resources to finish the experiment that will allow them to destroy the Triffids for good.