It’s Zombieland meets The Edge of Seventeen.
Our story begins inside a pet food factory. Dead chickens race along a conveyor belt towards a large industrial grinder. Suddenly, one of the chickens springs to life and begins feeding on the others. They, in turn, come to life and begin to feed on more dead chickens. Before the infection can spread further down the line, the birds are thrown into the grinder. The ground-up zombie chickens are squirted into cans and loaded onto a truck.
The tainted dog food is delivered to a pet store in a small seaside town. Lucy and Stuart are two openly gay teenagers living in the town. Home alone for the weekend, the two best friends binge-watch movies, unaware that a deadly infection is spreading quickly outside their door.
Lucy and Stuart flee in their pajamas when a pack of infected dogs force their way inside. Once outside, Lucy and Stuart are horrified to find zombie dogs, and their infected owners, running amok.
Running for their lives, the two teenagers take refuge in the town's shopping mall. Inside the empty mall, Lucy and Stuart shop for clothing and weapons. They are soon discovered and surrounded by zombies. Lucy and Stuart narrowly escape by using a pickup truck, on display inside the mall, to smash through the zombie hoard.
The two friends make a run for the only bridge out of town. As they approach, the bridge explodes and is destroyed. They quickly realize that their town has been quarantined and they will not be allowed to leave.
Pursued by a convoy of self-aware zombies, Lucy and Stuart race to the sea in a last-ditch effort to escape. Arriving at the town's marina, they find it, along with all the boats, ablaze. As the zombies, and a wave of air force bombers, close in, Lucy and Stuart salvage a scuba tank from the burned-out marina and drive off the end of the dock.
Lucy and Stuart ride out the napalm bombing by buddy breathing underwater. With the bombing over and the zombies eradicated, Lucy and Stuart surface to an apocalyptic sight.
Traveling back through the scorched landscape, Lucy and Stuart are confronted by a pack of badly burned zombie dogs that have managed to survive the bombing. They are rescued when a military helicopter swoops down and fires on the dogs.
When the helicopter lands, they find it crewed by zombies. Lucy and Stuart manage to outwit and kill the zombie crew, only to discover an uninfected pilot tied up inside. He explains that the infection originated in the meat supply and is spreading fast. Lucy and Stuart learn that the pilot was not infected because he is a vegetarian like them. Lucy and Stuart fly away with the pilot, in search of survivors.