A group of scientists at a top secret research center in the Phillippines are experimenting with a chemical compound called 'Death One'. It has the universal property of bringing the dead back to life. The military, who are funding the research, are more interested in its capability as a biological weapon for the substance causes tissue mutation and eventual death in living subjects. Professor Holder requests permission to leave the project, but before he can do so, the center is attacked in a commando-style raid. The two attackers, whom are presumably agents of another military power, make off with a box containing samples of 'Death One'. The box is damaged by the pursuers' gunfire and one of the commandos is shot and killed. The other accidently infects himself by touching the fluid leaking from the case, but manages to escape to a nearby hotel. He checks in and holes up in his room, seriously ill. He is apparently rotting away while still alive, and tries to stem the infection by cutting off his own hand with a machete.
Soldiers, wearing white bio-warfare suits, arrive at the hotel and find the man dead, but in the intern he has infected a bellhop and killed a maid. The head of the military clean-up crew, General Morton (Mike Monty) orders everyone in the hotel and the surrounding area to be rounded up and killed to prevent the infection from spreading. Afterward, General Morton orders the casualties buried in a mass grave. Despite a warning by Dr. Holder and his assistant, the man's body is then burned by General Morton's right-hand men, Tracey (Bruno Mattei) and Cheney (Claudio Fragasso), sending infected ash flying into the air for miles around. Meanwhile, a radio DJ in a nameless city comments on the situation whilst expounding ecological theories.
The following day, three U.S. Army soldiers on holiday from their base, are driving around in their jeep. They are Kenny (Deran Sarafian), Roger (Richard Raymond), and Bo (Alex McBride). The three soldiers encounter a group of three young woman heading along the same route by a large trailer. The group makes up Nancy (Ulli Reinthaler), Carol (Marina Loi), Lia (Deborah Bergamini), as well as Susanna, Jane, Jane's boyfriend Tom, and the trailer driver Joe. Nancy, Carol and Lia flirt with the soldiers through the back window, but soon chaos strikes as the bus is attacked by infected birds.
On another road not far away, a young couple, named Patricia (Beatrice Ring) and Glenn, are out on a drive discussing ecological issues. They discover many dead birds strewn across the road. When Glenn climbs out to investigate, his is savagely pecked by one, He soon starts to feel ill and the couple stop at a disused garage for help. While exploring the cobwed-strewn interior, Patricia is attacked by zombies. One of them, wields a machete, but she runs outside where the zombie strikes a gas line. Patricia lights it with her cigarette lighter and the whole garage, and zombies, are set on fire. Patricia is forced to drive away with the increasingly sick Glenn.
The three soldiers and the bus party seek help at the same hotel where the infected terrorist stayed, which is now abandoned. One of the girls, Susanne, has fallen ill after getting pecked by one of the infected birds. Kenny and Roger explore the building and find a crate full of guns left behind by the soldiers. Bo goes off with Carol in the jeep to look for help, but the whole area seems deserted. When the jeep breaks down, Carol wonders off in search for water. As she explores a residential apartment building, she is attacked by a zombie who pushes her into a swimming pool. Bo dives in after her, but when he pulls her out, she has no legs, having been ripped off by zombies in the pool itself. Carol then rises up as a zombie and tries to kill Bo, but he fights her off. Dozens of zombies swarm around to attack, and Bo is forced to run away. He flags down Patricia who is driving Glenn to the Santa Monica hospital. Bo persuades her to drive him back to the hotel to check on his friends. When nightfall arrives, Glenn dies and comes back as a zombie who attacks Patricia while shes still driving. Swerving the car, Patricia and Bo manage to throw the zombie Glenn out, only to be attacked on a bridge by zombies approaching from both sides. Bo is overwhelmed, torn apart, and eaten alive by the zombies. Patricia is forced to leave him behind and drives away.
At the hotel, the couple, Jane and Tom, are attacked and killed by a flying zombie head that emerges from a freezer. Susanna, the sick girl whose vital signs have almost disappeared, suddenly rises up and attacks Nancy. In the struggle, the zombie Susanna falls though a first floor window and drops 'dead' at Kenny's feet. Patricia finally arrives at the hotel in her car to meet the dwindling group. Before she can rest or explain to them about Bo's fate, the hotel is attacked 'en masse' by hundreds of zombies. Kenny and Roger hold them off by shooting them in the head, which they discover is the only way of stopping them. But despite 'killing' dozens of zombies, more and more keep breaking through the front door and windows. The five survivors are forced to flee out the back door where they take canoes on the nearby river bed and row away into the night. In the morning, the group stops for a rest at a remote river bank. Soldiers from General Morton's clean-up crew arrive and shoot the bus driver in cold-blood. Kenny and Roger fire back at the soldiers, hitting a few of them, before withdrawing into the woods.
Kenny, Roger, Nancy, and Patricia stumble through the dense jungle as soldiers swarm over every village and town in the area, indiscriminately killing people both infected and not infected, and burning the bodies in large funeral pyres. The four survivors hide out in an abandoned hospital. Nancy and Patricia find a pregnant woman left behind and about to give birth. Nancy tries to help the pregnant woman deliver the baby while Patricia wonders off and the two men get into another gunfight with General Morton's soldiers who have followed them to the hospital. Nancy is killed when a zombie baby bursts through the woman's womb and tears her face to pieces. Patricia encounters the zombie Glenn and has a fierce struggle with him in which she is forced to behead him to save herself. The three survivors make it outside the back door to a medical helicopter, only Roger is attacked by zombies as he tries to get on the helicopter. He is badly mauled, when the soldiers arrive and shoot Roger and the zombies to pieces. Kenny and Patricia manage to escape in the helicopter. Arriving over the city, they find it in flames in the mist of a full-blown war between the soldiers and zombies. Turning on the helicopter radio, they hear the DJ, who is now a zombie himself, dedicating a record to "all the undead around the world." The two survivors are forced to fly away from the city, with Patricia wondering if there is anything worth returning to.