Sarah and David are headed to their weekly couple’s therapy. They argue and are meant to each other the entire way. Along the way, they realize that traffic is light for Seattle at 4:30pm. The garage attendant is gone and so is the Therapist’s receptionist, Candy. When it goes tow minutes past their designated appointment, Sarah goes back to complain to the Doctor herself. They find Dr. Kelly eating the previous couple.
Dr. Kelly starts moving towards Sarah who is too shocked to respond. David gets her out of the way and fends off Dr. Kelley. Sarah stabs her in the back with a letter opener, but it only draws her attention. Sarah has trouble holding the doctor back. Dave beats in Dr. Kelley’s head with a shoe. They decide to call the police and tell them the truth about what they just did. Just then, the receptionist and the Wilson couple start reanimating and coming after them. They run.
David and Sarah argue some more in their car before the security guard returns and tries to eat through their vehicle to get to them. They drive away and turn on the radio, but it isn’t much help. They decide to go home as the prerecorded message suggests. Sarah goes to use the bathroom and is attacked by their neighbor, Jack. She kills him with the toilet seat and finally admits that David is right to call them zombies.
The couple watch the zombie reports on CNN. Afterwards they start planning by what they have learned from zombie movies. There is a knock at the door and Amanda (Jack’s girlfriend) asks to come into their apartment. Sarah asks if she was bitten. Amanda explains that when Jack went crazy, she wrecked the car and cut herself on some class. David eventually agrees to let her in.
Amanda tells them that Jack was bitten by a homeless man while they were on a beer run. In the parking garage was where he first attacked her. She ran inside and locked the door. Jack must have gotten Dave and Sarah’s spare key from the wrecked car to get into the apartment to get their own spare key. Sarah explains the zombie situation and how she had to kill Jack. Amanda seems strangely okay with it. After debating, Sarah and David tell Amanda their plan to leave the city. Amanda informs them that Jack has a gun safe. David and Sarah go to get whatever they can from the apartment next door.
They get into Jack and Amanda’s pigsty and find the guns. As they are about to leave with their load, they see the superintendent in the hallway. They start telling him their plan, but Sarah soon realizes that he is transitioning into a zombie. He is almost able to get Sarah, but David blows his head off. Back in their own apartment, Sarah finds that the house and cell phones do not work.
In their bedroom, the couple watches the local news anchor be bitten by the doctor who started the plague. They decide to visit Dave’s sister, Gina (who Sarah has never gotten along with) first because she is their closest relative. They sleep together.
The next morning, they get what little supplies they can find together and head for the parking garage. As they are loading the car, Amanda starts screaming because three zombies are coming after them. They shoot two and Sarah beats the last one to death with her gun. Dave is impressed and they head out.
They maneuver through the city to the highway just to realize it is filled with empty cars. Dave gets their small car around most, but realizes Sarah will have to move some eventually. Sarah shows Amanda how to load and shoot a rifle so that she can have some backup. This comes in handy when she has to ram a town car into another car to make room. Zombie strippers start chasing her, but she makes it back to the car and they drive off.
David realizes that they need to stop for gas because he forgot to fill up the previous day. They fill up at a gas station and then go into the store to loot supplies. Everything seems to go well until they go to leave and a group of zombies are outside waiting. They start out pretending to be zombies which seems to work until David drops the keys. The threesome starts shooting and heading for the car. They make it there and reload just to realize that they killed all the zombies around them. Amanda goes back in to use the bathroom. When she comes back, she explains that she had to fight a little girl, but wasn’t bitten.
A little further down the road, Amanda admits that she was bitten. Sarah crashes the car as Amanda transforms and David’s door is ripped off. David shoots the zombie Amanda and then the ones trying to get him from the street. They get off of the highway, which the zombies can’t seem to figure out. They find a car dealership and go inside to keys for a newer, bigger vehicle. Sarah is attacked while David is listing makes and models. She is saved by an Asian girl, Lisa.
Lisa invites them to her apartment to share her perishable foods and they agree to go. She tells them how she has lost everyone she knows. They offer to take her with them because she seems to be able to handle herself. She refuses, figuring that it is safer alone and where she knows where everything is. Dave and Sarah leave her and go back to the car lot. David already has a key for a newer Escalade. They transfer everything they can from the old car. They set their first car on fire to cremate Amanda, but that attracts a horde of zombies and they have to leave quickly.
Driving down the road, both David and Sara are quiet. She start talking to him about how they’ve learned and they couldn’t have known about the bathrooms. They go through the list of people they knew and killed. Eventually, they turn on the radio and find that the zombies are spreading all over the west coast; the disease will soon be global. They decide to stick with their plan and go to Longview.
Since it is starting to get dark, the couple decide to stop for the night. Dave picks a rundown casino to stay at. Sarah questions this choice, he tells her to trust him or take the car and leave. They go inside together and find a lot of gambling zombies that don’t seem to notice them. They decide to look for survivors throughout the casino/hotel.
They go into the kitchen and are attacked by zombies. They are saved by a man named William who takes them to meet their 30-some survivors. David and Sarah quickly realize that this is a cult and it won’t be as easy to leave as they had hoped. They end up locked in a guarded hotel room and decide to take their chances with the zombies by climbing out the window. They braid the bed sheets together to lower themselves out the window and onto an awning. Sarah makes it down safely, but David hurts his leg in the process. As they look for a car, the cult comes after them but are quickly distracted by a horde of zombies. Dave spots an old Caprice with the keys in the ignition. They get in just before the zombies reach them. Sarah flings them away with the car. They see William get bitten before driving off.
Sarah pulls over in the park under a streetlight. David crawls into the backseat and Sarah goes through the glove box to see what they have. They find a GPS system, a handgun, some ammo, and a bottle of whiskey. They check out David’s leg, hoping it is only a deep bone bruise. David admits that he was wrong about the casino. They decide to let the past go and move on.
The couple uses the GPS to find a sporting goods store. They start looting the guns and then split up to find blunt objects to use as weapons. As Sarah is at the front of the store gathering snack items, she is attacked. She kills the zombie, changes her clothes, and comments about how they’re having fun.
They loot a small local grocery store next. Sarah finds a girl that killed herself by overdosing who did not become a zombie. They are able to get some food and medications that could be helpful in healing David’s leg. They have to fight off more zombies before they get back on the road to continue their journey.
They make it out to where the roads are clear. Dave turns on the radio and eventually finds a girl broadcasting on an AM station from Portland. She warns that the government isn’t interested in survivors; they are trying to cover it all up by destroying the city. Sarah breaks down and has to pull over. David suggests they give up on Longview and head either east or north. Zombies appear and Sara is so mad that she decides to run them over. She explains that they still need to go to Longview to see if his sister is alive.
When they get to Longview, they see that it was around the time of the annual fair. They notice the Ferris wheel is still going and head that way to check for survivors. On the way, Sarah goes to soot a zombie, but someone gets it with an arrow first. They see Conrad, Gina’s neighbor, and tells him what is going on. They lost a quarter of their population, but Gina is alive and at home. David and Sarah tell him that Seattle is pretty much gone. They leave for Gina’s house.
Arriving at their destination, they knock on Gina’s door. She tries to blow them away with a shotgun before she realizes who they are. Once inside, they realize that Gina is in denial. David makes her snap out of it and realize they can’t stay in Longview. Sarah is able to check her email and sees that her dad left San Diego for Chicago, which is supposed to be zombie free.
The power goes out and David goes to check the fuse box in the basement. Conrad comes along and Sarah lets him in. She goes to check on David to give them a minute because Gina has a thing for Conrad. When she goes upstairs to check on them, Conrad has bitten Gina. Sarah kills him and yells for David. Gina explains that he seemed normal, kissed her, apologized, and then bit her. She says it isn’t Sarah’s fault and explains what they must do. Gina and Sarah come to an understanding before Sarah kills her.
They bury Gina and Conrad and decide to head to Chicago as Sarah’s dad suggested. Along the way, they plan to help people who are hiding out and trying to survive.