Best friends Ash and Iris are hanging out celebrating Ash's birthday. They are joined by Ash's boyfriend Kevin and his friends Ty and twin sisters Destini and Lindsey. Iris is indifferent to them all and doesn't join in their conversation. Kevin surprises Ash with highly sought after tickets for the Festival Of The Living Dead but Ash tells them she cannot go as she has promised to babysit her 10-year-old brother, Luke. Iris offers to watch over him and the friends all set off to the festival. Ash takes an antique gun with her she says her grandfather used to shoot zombies in the 1960s.
Arriving at the festival entrance the friends see the line is backed up and they drive down an entrance for staff, Kevin hits a man and the car is totalled resulting in minor injuries apart from Lindsey who has broken her leg. Destini stays with her while Ash, Kevin and Ty go to fetch medical staff at the festival. Soon after the man they hit is revealed to be a zombie who quickly attacks the twins.
Back at home Iris has her friend Blaze come over and she confides in him that Ash has changed since meeting Kevin. They watch videos from the festival and see a vlogger snorting what he claims to be meteorite. Another video shows him bleeding and then snarling and attacking a paramedic but the friends believe it to be a fun prank. Blaze says Iris should not miss the fun and he and Luke convince her to try sneaking into the festival. Which she reluctantly agrees to. They arrive and find the entrance closed off so also take the road marked off for staff.
As Ash, Kevin and Ty arrive inside the festival they notice some people are acting strangely but proceed to the medical facility where they walk inside they narrowly miss seeing the chewed up corpse of a staff member. Inside they find it deserted apart from a woman who warns them they are in danger but Ty convinces them she is tripping and steals her bag of shrooms. He leaves as Ash attempts to calm the woman but Ty calls them outside and tells them he has called 911 and they are on their way but he is lying as revealed when he puts his phone in his pocket and it says call failed.
Ash hears her favourite band start playing and Kevin rushes her towards the music. Explaining that they may as well enjoy themselves now help is on the way to the twins. In the crowd of people Ash notices some festival goers are now bloody and attacking the crowd which quickly turns into utter chaos as people are attacked and devoured including the band on stage.
Meanwhile, Iris, Blaze and Luke encounter Destini walking in the road. Iris helps her into the truck and she explains the man killed her sister and she had to run but she was bitten in the process.
Ash is separated from Kevin and Ty as the festival erupts into chaos and most of the crowd are attacked and eaten as they flee. Ash is besieged by a zombie and almost bitten when Iris arrives and blows its head off saving her friend. Ty and Kevin slowly sneak around the zombified crowd who are busy eating the bodies. They find a police car with a dead officer inside and Kevin attempts to retrieve a gun but is too scared so Ty gets it instead but is forced to shoot a zombie who attacks him drawing a crowd. They quickly retreat.
Ash and Iris are joined by Blaze, Destini and Luke who explain the truck died and they were worried about the others. Suddenly the band who were on stage attack and the group flee back to the medical center where Ash holds the zombies off as the others get inside where they are reunited with Kevin and Ty. Destini is almost catatonic and crying over her sister much to Ty's annoyance. Iris scolds his indifference to others pain and the group argue over the best plan of action of either staying or leaving the building which is quickly becoming surrounded. Suddenly they are attacked by zombies from the medical wing, however they manage to barricade themselves inside a room.
Luke begins to panic and Ty threatens to shoot him but Ash explains he needs insulin as he is diabetic, an uncaring Ty says he doesn't care and won't allow anyone to leave and Kevin agrees. Ash dumps Kevin immediately and he quickly turns nasty and berates her before she and Iris leave to find insulin.
Ty becomes more unhinged, imagining Luke as a zombie, he once again threatens to kill the child but Blaze defends him which leads to Ty punching him and cruelly tipping him out of his wheelchair, as this happens Destini, who has turned attacks Kevin and as he begs Ty for help he shoots his friend and allows Destini to bite him. He then evilly pushes Blaze into the room leaving him and Luke to be devoured bur he awakens just in time to see Destini feasting on Kevin, he is forced to put her down but in doing so he shoots the glass door allowing the zombies inside, but thinking quickly he smothers himself and Luke in zombified blood to mask their scent causing the zombies to bypass them both. Meanwhile, Ash and Iris find insulin in a bloody ambulance and begin heading back to the medical facility when they are split up.
Back with Ty he is chased by a hoard of the undead when he stumbled into a crater and is face to face with a glowing meteor rock and is besieged. Ash, Blaze and Luke eventually meet up and manage to find some car keys, they take respite in a fairground ride when Ty suddenly turns up and holds Luke hostage.
An infected Ty demands the group accompany him as he finds a way out as he believes there is a cure. He forces Ash to draw attention to herself so he can get pass safely as she fights her way through countless undead she finds a now zombified Kevin who is feasting on flesh, she sadly shoots him and then notices Iris climbing up a giant burning man to escape a hoard which catches alight. Zombies begin the climb the structure when Ash saves Iris and clears a path for her to escape as numerous zombies are set of fire and killed.
As night turns to day Ty, Blaze and Luke find the car but Lindsey is near by and now mysteriously deformed. She attacks Luke but Blaze bravely put himself between the two and is pulled from his wheelchair as Ty forces Luke inside the car and drives away. Over the radio they hear an announcement that the festival will be bombed in moments. As they drive Ty laments that it was all worth it to save himself and he would do anything to save himself but shockingly Luke reaches for the gun and shoots Ty dead.
Back at the festival Ash, Iris and Blaze take one last stand and put down many zombies but jets fly over head and begin bombing. Blaze reveals he is bitten and forces the girls to run while he sacrifices himself as a distraction. Moments later Luke returns and the movie ends as Ash, Iris and Luke drive back home.
