Mysterious Parasite Outbreak Wipes Out Most of Humanity by Turning Them Into Zombies

On the news, reporters mention that an epidemic  is spreading through China, so the Department of Health has announced a quarantine. This new  illness appears to be caused by a small wormlike parasite so the public is calling it the “worm  flu”. It isn’t in the air like the common cold, it can only pass on to a new person through blood  transmission.

In California, Emma is still having trouble getting used to her new school and doesn’t  fit in while her sister Stacey has many friends and even a boyfriend. After class, Stacey notices  that Emma keeps staring at her crush Evan and offers to give him a ride home. Their dad and  Biology teacher Michael is the one driving so the trip is rather awkward.

Stacey keeps telling  Emma to do dirty things through text messages, which triggers an argument. The girls’ mother,  who is currently in another state, calls them to check on them and the conversation is tense  between her and Michael. Later during dinner, Michael scolds Stacey for using her phone at the  table.

Stacey snaps and insults his attempts at being a real family when it’s obvious that  the situation with their mother is awful, so Michael sends her to her room. After dinner  Emma video chats with Gracie, who is having a special tea because her mother has been coughing  right on her face. They watch a video of a sick-looking man getting into an elevator and  biting another person, which rumors say it’s a consequence of the worm flu.

At that moment a  paper plane flies through the window and Emma opens it to find a drawing from Evan. She writes  her phone on it asking for a call before sending the plane back through the window. Then she runs  outside to meet with Even, who is calling her at the same time.

The teens share a sweet moment that  is interrupted by Evan’s abusive step-father Bill, who teases them for a while before going back  into the house. Then Emma kisses Evan’s cheek and goes back inside too. She sees her dad and asks if  things are ok with her mom, so Michael admits that things are tough because he just got a demotion. 

The next day Michael gives a class on parasites, showing some nasty videos that teach them how to  remove them. He’s even brought a living larva in a jar and explains the worm flu appears to be a  parasite as well. Some parasites take control of their hosts, which Michael proves by showing a  video of a rat under the control of a parasite being fearless around cats.

Evan compares this to  zombies. Suddenly Gracie starts coughing blood and runs away. Emma follows her out and finds her  having a seizure on the ground.

She calls for help and a boy comes over to watch over Gracie  while she runs to find the school nurse. Suddenly Gracie stops moving only to then throw up a  bunch of blood on the boy’s face. Moments later, a government agent gives Emma a check-up  and asks about Gracie’s habits lately, so Emma explains that Gracie’s mom recently came  back from San Francisco.

In the end classes are canceled while the military surrounds the town  to be sure nobody leaves or enters. Michael learns his wife is stuck in the airport and can’t  get a cab, so he’ll have to go pick her up. The sisters hitch a ride to go home and notice some  neighbors getting ready to leave town.

At home, Emma sees on the internet that California has  officially been declared infected and that the parasite is mutating quickly. She tries calling  Gracie, but she only gets the voicemail. Suddenly she hears a weird noise and looks out the window  to find a deer in the garden, but when a noisy helicopter flies by, the deer just disappears. 

At that moment Michael calls the girls to tell them they’ve closed the roads and he’s stuck, so  he won’t be going home soon. He’s heard the whole county’s going under quarantine, thus he wants his  daughters to stay home and not invite everyone. In the evening, Emma is changing and gets a text from  Evan saying he can see her through the window, but the teens just use the chance to flirt shyly.

Then  the sisters notice they don’t have much food left, so they make brownies to eat while watching  the president’s latest speech. He promises that they’ll contain the parasite effectively if  everyone follows the protocols accordingly. When Emma goes to the kitchen, she hears a weird  noise outside so she approaches the door and looks through the mailbox, only to get startled  when a shadow moves.

Emma is scared but Stacey thinks she’s exaggerating, thus she opens the  door to reveal there’s nobody outside. Then someone jumps out to grab Emma by the neck and  makes her scream, however it’s a prank Stacey planned with her boyfriend CJ. A disapproving  Emma reminds them of Michael’s rules, but the couple ignores her and runs to Stacey’s room to  get dirty.

Meanwhile Emma checks social media and sees a post from Gracie’s parents saying she’s  in stable condition. In the comments, she finds a video from a conspiracy theorist saying this is  worse than what the government says. Emma can’t hear the video well because the noises coming  from Stacey’s room are too loud.

The next morning, Emma wakes up to the sound of CDC vehicles going  through the neighborhood delivering disaster kits. The sister and CJ open their boxes to find field  rations, a flare, a flashlight, a first aid kit, and masks among other things. A note tells them  to immediately contact the authorities if anyone gets symptoms.

CJ and Stacey don’t take anything  seriously, but their fooling around is interrupted by a call from the sisters’ mother, who is still  stuck at the airport. Moments later, Emma watches the news and learns a bunch of infected patients  have gone missing. Stacey announces that she and CJ are leaving for a party, ignoring Emma when she  tries to stop them.

After they’re gone, Emma gets a text from Evan saying he’ll see her at the party  because Stacey used her phone to ask him. Now Emma has to break the rules too. The party is inside an  abandoned building and full of teenagers drinking, but Emma is the only one wearing a mask.

There’s  a sick-looking boy covering his face with a hoodie and strangely sneaking around. Emma finds Evan so  they can dance and share a drink before looking for some privacy. Most of the rooms are taken  by naughty couples, so they end up sitting in a bathtub.

Evan tells Emma that he likes her and  gets ready to kiss her, but they’re interrupted by hearing Stacey yelling. It turns out she’s in  an argument with another girl and CJ because she found him cheating on her. While Emma tries to  console her sister, hoodie guy grabs a girl by her jacket and another boy comes to her defense. 

Hoodie guy drops the girl and turns around, revealing red eyes and dark veins that indicate  he’s infected. He then throws the other guy off with admirable strength and everyone panics when  they realize hoodie guy is attacking. The sisters run to hide in another room and look through a  hole in the wall to see everyone running away from the attack of the infected guy.

Emma and Stacey  stay quiet until they don’t hear any more noises and when they look out again, they see a girl  trying to sneak out. Unfortunately she makes some noise and the crazy guy finds her to immediately  kill her. When he’s done feeding on the body, the parasite can be seen peeking out of his mouth.

The  sisters wait for him to leave and they come out, trying to move carefully. Sadly they accidentally  kick a bottle on the floor and hoodie guy comes after them. Stacey pushes Emma away and hoodie  guy spits blood right on her face.

Then he goes after Emma, removing the mask when she tries to  put it on. After some struggle, Emma manages to punch him to bring him down. At the same time,  a parasite enters Stacey’s body through her eye, but she doesn’t tell Emma about it.

The infected  guy quickly recovers and tries to attack again, only for Dave to appear behind him and knock him  out with a piece of wood. At that moment the teens hear the police sirens getting closer, so they  escape through the back door. Later at home, Stacey washes off all the blood.

Emma continues  to watch the conspiracy theorist and learns that people are going crazy all over the world, so  he thinks the parasites can communicate with each other with a network only them can hear.  Infected people often go missing because they gather to form nests. The video is interrupted by  a message from the government reminding people to alert the authorities if they see any symptoms. 

Next Emma tries texting Evan, but he doesn’t answer and turns off the lights in his room. The  next day, some army scientists scan the girls for any signs of the virus and ask them if they were  in contact with an infected person, but they both say no. After the scientists leave, Stacey feels  something weird on her neck and lets her hair down to cover it.

On the news, they show how every  street is empty and the military marks every house that they’s been cleared with graffiti. At  that moment the sisters get a call from Michael, who tells them to lock every window and door and  to get his gun. Before he can say more, the call gets cut.

While the girls notice that the phone  has no signal, the news inform that the Chinese government has started to bomb areas with lots of  infected people. However the news get cut too and an emergency broadcast appears to announce martial  law has been declared. The sisters go looking for the gun and Emma finds her mom’s wedding ring,  proving things aren’t well between her parents.

Stacey finds the gun and shocks Emma by handling  it pretty well, revealing Michael used to take her to the range. In the evening, a neighbor shoots  his flare to ask for help because someone's infected. Emma tries texting Michael but her  messages can’t be sent because the network isn’t working.

When the soldiers arrive, they drag an  infected woman away while ignoring her husband’s protests. Soon more and more flares appear in the  sky, indicating the parasite is spreading through the neighborhood very quickly. The sisters decide  it’s getting too dangerous and leave in their car.

Emma tries inviting Evan to come along but Bill  closes the window. Moments later on the road, the sisters find the road blocked by the military.  Stacey tries to convince the soldiers to let them pass, but Emma calls her over when she sees  a truck approaching at great speed.

As Stacey runs back into the car, the crazy truck gets too  close to the barrier and the soldiers open fire. Since they’re distracted, the girls manage to  get away and drive back to their home. The next morning, Stacey notices a bump is forming at the  base of her neck but continues to keep it secret.

A government vehicle does its rounds and announces  that it’s now illegal to harbor an infected human. Getting worried, Stacey heats up a pin and tries  popping the bump, only for something to move under it and stop her. That night Stacey says she  must confess something, but she gets scared at the last second.

Instead of telling Emma about the  parasite, she shares that Michael cheated on their mom with one of his students last semester. Emma  gets upset because she wasn’t informed of this but it’s interrupted by Stacey coughing. Suddenly  they hear Evan pounding on their door and begging to let in.

Ignoring Stacey’s protests, Emma opens  the door and Evan rushes inside, quickly closing the door again while explaining Bill is infected.  At that moment Bill starts pounding on the door too and the three teens hold it close until  he’s gone. While Stacey runs to get the masks, Emma looks through the peephole and Bill reappears  to spit blood on the door.

Then Bill runs around the house and jumps through the window, making the  teens fall and drop the gun. He quickly recovers as the parasites move on his neck and come out of  his ears, slowly approaching Emma. However before he can infect her, Stacey retrieves the gun and  shoots him dead.

This causes Emma to have a panic attack and while Evan tries to calm her down,  Stacey drops the gun and it accidentally fires as she collapses. This is followed by a seizure  and coughing blood, confirming Stacey is infected. Moments later, Stacey is locked up in the  bathroom.

Evan thinks they should hand her over to the soldiers, but Emma refuses to lose her sister.  To trick the army, she goes outside and paints graffiti on her house indicating everyone inside  is healthy. A few hours later, Stacey is begging for food and tells Emma to leave her before she  hurts her.

Emma refuses again and holds her hand, reminding her that sisters look for each other.  Next Emma starts researching how to handle parasites, remembering the video Michael showed  them at school. When she needs a break she sits on the roof and tries to use her phone, but there’s  still no signal.

Evan consoles her as she cries because she thinks she’ll never see her parents  again. Meanwhile CJ enters the house and looks for Stacey. He’s learned that the army has left  town so people are leaving too, and now he wants to leave with her.

CJ finds her in bathroom and  holds her hand through the gap in the wood boards, only for Stacey to say he really hurt her and  start feeding on his arm. Emma and Evan hear the screaming and run back inside to find CJ already  dead. Stacey cries and apologizes for her actions, explaining the parasite forces to do these things. 

Afterward Evan buries CJ in the garden next to Bill while Emma crushes a bunch of sedatives  that she mixes into a meal. Then she feeds it to Stacey and even offers her hand to show  she still trusts her. Once Stacey falls asleep, Emma and Evan unlock the bathroom and use the  method they’ve learned in the video.

The bump on Stacey’s neck moves when Emma touches it, so she  quickly covers it with tape to choke the parasite. The creature comes out for air and Emma catches  it with tweezers to start pulling. To her shock, it’s an extremely long worm and this is taking her  longer than she expected.

Suddenly Stacey wakes up so Emma steps back and watches how her sister  fights the worm trying to control her. It even tries to hold her arm, but after lots of struggle  Stacey pulls it out and Evan repeatedly steps on it to kill it. The next day Stacey is already  feeling human again and Emma notices her neck bump is almost gone.

Outside, an army truck announces  that this area is now under official evacuation so everyone must come out, yet Emma still refuses  to leave because she’s afraid of what they’ll do to Stacey. Sometime later the army starts using  scanners to find people hiding in their homes, which Evan hears on the radio. Meanwhile Emma  checks on Stacey and finds her full of worms, but it turns out to be a dream.

At that  moment Evan calls Emma to the kitchen to show her all their food is gone, and the  bloodstains indicate Stacey was involved. Emma goes looking for her sister and finds her  running away from the house, so she chases after her with Evan. They follow her into a neighboring  house, where they find a dead family.

Judging by the father’s gun, he killed the others before  self-deleting. The duo follows bloody footprints on the floor and enter a storeroom, where they’re  shocked to see a nest of infected people standing around Gracie. She’s on the ground extending  her worms towards the others.

As Gracie opens her eyes, Evan and Emma try to step away, only  to accidentally hit a toy and alert the infected ones of their presence. The duo immediately runs  away as the infected people chase after them, even appearing outside the house. They run  upstairs and try to close a door only for an enemy to push back, so Emma shoots him.

After Evan  throws some furniture to block the door Emma finds Stacey, who can’t stop hearing the parasites’  voices telling her to kill her sister. A crying Stacey begs Emma to delete her and at first Emma  refuses, however Stacey suddenly transforms and tries attacking Emma, who immediately shoots  her down. Emma wants a moment with her sister, but the infected ones are breaking down the  door so Evan forces her to escape through the window.

As the duo climbs on the roof, they  discover the military is bombing the area. They decide to jump into a swimming pool, allowing  the water to protect from the explosion at the last second. Emma and Evan wait underwater for as  long as possible and when they finally resurface, they find their town in ruins.

Sometime later, the  duo reaches the barrier on the road and discovers all the soldiers are gone. They stop at a gas  station and Emma finds a family picture on the window. It was left by her dad with a note telling  his daughters to meet him and their mom at their uncle’s house in Washington.

Emma and Evan then  steal a car and share a kiss before they leave.