It’s a normal day in Hong Kong when suddenly the biggest tsunami in history hits the city,
quickly flooding the streets and filling up the buildings. People run away in panic trying to
find a safe spot where to hide, but the water is faster than them. Only those who manage to get to
a floor high enough survive, and Hong Kong loses most of its population in just a couple of hours.
Five years later, Asha still has nightmares of the horror she felt that day. However every morning
she bottles up her fear and pushes through to keep on surviving. She’s living in a high building that
is in ruins, and she takes advantage of the trash to keep her things hidden from potential enemies.
She’s been savaging anything useful for the water for years and has created hiding spots all over
the apartment, like making a hole under the couch cushions. Every morning, she goes to the roof and
gets some clean water from her secret stash, which is also carefully hidden. After drinking some tea,
she listens to the radio, but she ignores the recorded message informing about a government
shelter with supplies and chooses music instead. She’s careful to use headphones to avoid making
extra noise. Next she uses a towel to gather the morning dew, which she adds to her stash of water
bottles. She also measures all the bottles to keep track of how much clean water she has left,
and she can’t help worrying because it hasn’t rained in a while. Once her chores are done,
she eats instant noodles while remembering the beautiful restaurants with delicious food she
used to visit with her friends. Afterward Asha uses binoculars to watch over the area. Only the
top of the buildings can be seen sticking out of the water, and occasionally those buildings would
start crumbling down. She also makes sure that the few surviving neighbors are still in their
apartments. Suddenly she sees a box floating in the water and rushes to a different window,
where she’s installed a makeshift harpoon-like mechanism that she uses to scavenge. With one
quick shot she manages to catch the box, but when she tries to pull it in, something in the water
drags the box down and makes her hit the edge of the window, hurting her arm. Asha ignores the
pain and keeps on pulling against the mysterious strength, falling back from the whiplash when the
creature finally lets go of it. Then Asha brings the box inside, and the animal has its revenge
by sending a wave against her. The box mostly has trash in it, but she also finds a bottle of
alcohol. On her way back to the roof, Asha stares at the door at the end of the corridor before
moving again, clearly upset. On the roof, she uses the alcohol to clean her wound before wrapping it
up and drinking the pain down. In the evening, she hears screaming and looks outside to discover two
boats of violent scavengers have come by and are attacking the neighbors. There’s also a man on the
other roof looking at her building, so Asha hides for a few seconds before looking again. It seems
the boats are coming to her place, so she rushes downstairs, hides all her daily things, covers her
mattress, and even throws some dirt on the hallway to make it look live-in. Then she hides behind a
fake wall in a closet, making sure to keep silent as the scavengers get into the room and begin
looking around for food, even checking the closet. Thankfully they don’t find anything, but Asha gets
startled when she hears a shot - a boy just shot his gun because he thought something moving, but
it was a mistake. After the group is gone, Asha cries in relief and tries to calm herself down
with a nice memory. Before the tragedy happened, Asha had gained a half-sister and she took her
out for a meal to start bonding. The next day, she finds another box and among all the junk inside,
she’s excited to find a jar of honey. However her happy moment is ruined when she sees a body
floating in the water. Sometime later while Asha is busy, someone sneaks inside and starts taking
things from Asha’s secret spots. Asha thinks she hears something but can’t see anything, so she
ignores it for now. When she gets ready for bed, she hears another noise and goes to investigate
with her flashlight, but once again there’s nothing. Next she washes her face and leaves the
soap out on purpose to finally catch the intruder, who turns out to be a little girl. Asha grabs the
shoulder to confront her, but the child kicks her and runs away. She takes a few more things
including Asha’s makeshift lamp and goes down the corridor, but before she can open the mysterious
door, she hears Asha coming and leaves again. That night, Asha dreams of the time she went shopping
for clothes for her sister’s birthday, and how she told her best friend that she was eager to
leave her parents’ house. When she wakes up, she notices part of her food stash is missing, so Asha
begins following the empty wrappers on the floor and finds the girl sleeping with the lantern. She
doesn’t have the heart to wake her up, so she goes to do some cooking instead. When the girl
finally awakens, she goes around looking for more hidden compartments. Inside a fake outlet,
she finds an envelope with pictures of Asha and her sister, only to be caught red-handed.
The child runs away and Asha hurries to put the pictures back in their place, not noticing she
accidentally dropped one. Afterward she makes a second portion of noodles and brings it to the
child while remembering the night of her sister’s birthday dinner. Their parents gifted her the
family’s necklace, which made Asha angry because as the first child, she was supposed to get it. An
argument ensued and Asha ended up leaving. Back to the present, it’s shown that Asha is wearing that
necklace now. The girl ignores the food offer, so Asha leaves it next to her and leaves. The child
eats it all and moments later, she notices Asha left a mattress for her too. She doesn’t use it,
but the next morning, she gives Asha back all the things she stole. For lunch, Asha makes
two portions of noodles again and leaves one for the girl to then go eat on the roof. However the
child soon joins her and copies everything she does, causing them to laugh and bond. It makes
Asha remember the happiness of her old life again. In the evening, the girl finally accepts to take
the other mattress and sleeps next to Asha. Soon she starts crying and tries to hide it, but Asha
tells her it’s ok to cry and be scared. The girl misses her family but thinks she’ll see her mom
soon because she’s building a boat to find it. She also mentions her name is Hei Hei. After another
night full of nightmares, Asha takes Hei Hei with her to the roof to go through the routine. Hei
Hei is playing around with the door and removes the tape Asha put on the lock, so when the door
accidentally closes, they can’t open it from the outside. Asha is upset, but Hei Hei immediately
shows her she can pick locks and opens it again. Later while Asha is getting a new meal ready,
she realizes her necklace is missing. At that moment she hears some noises and looks out the
window to discover the scavengers are back, so she asks Hei Hei to stay silent while they wait until
they’re gone. Later while Asha helps Hei Hei get clean, the girl asks her to leave together, but
Asha refuses. She says this is her home and that there’s nothing out there anyway. Then Asha asks
Hei Hei if she took her necklace, but Hei Hei says she didn’t and runs to another apartment, offended
by the accusation. In the evening, Asha has dinner alone and notices there’s water missing, so she
goes to investigate and discovers Hei Hei took it to wash. This triggers another memory of her
hearing news of a typhoon coming to neighboring countries, and how she fought with her mother,
who wanted her to get married and be a good wife. That night the nightmares get worse and Asha keeps
seeing all the bodies in the water. When she wakes up, for a second she mistakes Hei Hei
for her sister. Afterward, Asha teaches Hei Hei how to deal with the electricity in the building,
but Hei Hei interrupts to ask about the door at the end of the corridor. Asha asks her to ignore
it because that room stinks and if they open it, the smell will spread everywhere. Another memory
shows Asha watching the news, which was reporting the complete destruction of Singapore by the
floods. Her mother turned off the TV and told her about the next family meeting, but Asha couldn’t
go. Another argument ensued and Asha told her family they made her feel like a prisoner before
leaving the apartment. Back to the present, Hei Hei is using the radio and hears the message about
the shelter, so she rushes to Asha to ask to go there. Asha refuses, explaining it’s dangerous to
go out. An argument ensues, so Hei Hei calls Asha angry and bitter and leaves the room. Following
her into the other room, Asha discovers Hei Hei is building a raft with trash, she’s also got a flare
gun. Asha immediately takes it from her and makes a confession: some time ago, she tried to leave,
and the situation out there was so horrible that she had to come back. After they reconcile,
Asha remembers how her sister followed her out of the apartment after the fight with her parents,
asking her not to go. Asha explained it was time for her to move out, but she promised they
would still hang out. The next morning it’s finally raining, so Asha and Hei Hei rush to
the roof to gather lots of water and put it away properly. While they’re working, Hei Hei notices
that Asha’s necklace had simply fallen. Then Asha discovers the photo that got left behind and she’s
overwhelmed with memories, so Hei Hei comforts her and reminds her they have each other. When Asha
goes to bed, she’s surprised to find something under her pillow: it’s her necklace, which fell
because the clasp is broken. Feeling bad about how she treated Hei Hei, the next morning Asha
begins working non-stop until she manages to build a raft. Hei Hei gets super excited, and
Asha remembers the night of the argument again. Her sister was trying to tell her she left the
necklace in Asha’s jacket when suddenly people in the street started to run in panic because there
was a huge tsunami behind them that hit the streets in seconds. Back in the present, Asha
decides to gift Hei Hei her necklace. Sometime later, the duo gathers supplies to get the
raft ready to leave. Hei Hei is listening to the radio and the headphones accidentally disconnect,
causing the music to loudly echo in the room. Asha rushes to turn it off but soon they hear
the voices of the scavengers outside. Panicking, the duo rushes to hide all their personal objects
as fast as possible, then Asha pushes Hei Hei into the hole behind the fake closet wall.
There isn’t enough room for both of them there, so Asha will be hiding in the stinky room. Soon
the scavengers enter through the window, but Asha hides just in time in the stinky room, where she
finds her old family pictures because this is her old apartment. The scavengers start a much more
violent search this time, destroying anything they could find including the raft. A guy comes to the
stinky room and gags at the putrid smell, but he keeps moving and removes some old sheets only to
find the bodies of Asha’s parents, causing him to puke. At the same time Asha throws out too while
remembering the night of the tragedy. The wave was taking down everything in its path, killing
dozens of people per second. Everyone started to push each other for a chance to survive,
so Asha dragged her sister into a building to take the stairs, but soon the crowd was following them.
Back in the present, the scavengers are taking all the food and staring at Asha’s pictures. The boy
finds the closet and notices something weird, so the other scavengers help him move the fake
wall and they capture Hei Hei. Asha hears all this from her hiding spot in the stinky room and once
again has a flashback: when they were going up the stairs, the sister tripped and fell behind,
so she was trampled by the crowd. Asha was panicking and kept on running, not noticing
her sister was missing until she made it to the roof. Suddenly Asha hears a scared Hei Hei tell
the group where she is and the scavengers quickly find her, knocking her out. When she wakes up,
Asha is tied up and the foreign scavenger tries to take advantage of her, but at that moment
the leader calls him over. Moments later, Hei Hei and all the supplies are taken to the scavengers’
boat. Asha is soon dragged out too and looking at Hei Hei reminds her of her sister, making her
realize she can’t make the same mistake again. She pulls at the rope, but the guy pulls back
and makes her fall into the water. Luckily there’s a broken CD nearby, so Asha uses it to attack the
man, which causes him to angrily try to drown her. After some struggle, Asha finally reaches
the flare gun in her pocket and shoots the guy, killing him. The other scavengers hear all the
noise and come back into the building, but they don’t see Asha. As the group splits to search,
a big guy hears Asha cry and comes after her, but this is part of her trap: she makes him
fall with some rope, then uses a guitar to beat him to death. Next, she takes his knife and runs
into another room to turn on the radio. Soon a scavenger follows the noise and Asha jumps on him
from behind, stabbing him with the knife. It’s not enough and the guy starts fighting Asha, throwing
her on a mattress to try to choke her. Thankfully she manages to reach the knife and starts stabbing
him repeatedly until he’s dead. Then the female scavenger also hears a noise and finds a can with
fire inside. Asha surprises her by throwing oil on her and pushing her into another room, where she
sets her on fire before blocking the door to let her burn slowly. The leader hears her screaming
and moves in that direction, but when he takes the stairs, Asha jumps on him to stab him. Another
fight ensues during which the leader hits Asha a couple of times before trying to choke her. Asha
continues to struggle and reaches up to grab the light tube, causing darkness to take over as she
beats the guy to death with it. When she turns on her flashlight, the boy shows up and opens fire,
so Asha immediately runs to the roof. The boy goes after her and as soon as he steps outside,
Asha closes the door after having removed the tape, trapping the scavenger on the roof. The
boy starts begging for help with an innocent voice and Asha considers taking pity on him,
but soon he starts shooting at the door so Asha leaves. There’s only one scavenger left
on the boat, watching over Hei Hei. Asha goes to the window and uses her harpoon-like device,
but she misses the shot and it falls in the water. When the guy moves to check on the noise, Hei Hei
uses the chance to push him off the boat, but the man grabs her and makes her fall too. A desperate
Asha jumps into the water to save her while the man resurfaces nearby, only to be eaten by the
sea creature. After a few seconds of silence, the duo resurfaces too, all safe and sound. They swim
to the boat and finally get going, knowing that all the supplies the scavengers stole will keep
them going until they find the shelter. That night, Asha finally sleeps without nightmares.