The closest Alex Harley has ever been to a zombie is on his game console. Trapped in a dead end job and spending his weekends gaming, Alex is coasting through life at his own pace. But one fateful weekend, he agrees to go hiking with his pal Mike. Mike's girlfriend, Elena, is bringing her friend Lucy along and that is good enough reason for Alex to endure grueling hikes along a mountain range in Wales.

Alex Harley wasn't cut out to be a survivor in a zombie apocalypse. And now he may have made a fatal mistake. Going ashore to find news of his brother and parents, Alex is attacked by feral survivors. When he gets back to the harbor, he finds his boat . . . and Lucy . . . gone. Stranded on the mainland, alone and vulnerable, he seeks shelter from the shambling zombies and the roaming army patrols. He meets a group of survivors who seem to be on a mission. They have found a way to get a message to the survivors in the camps. 

In a desperate bid to save Lucy, Alex goes in search of the secret government facility on Apocalypse Island. If the scientists there created the virus, then surely they have a cure. Alex will go to any lengths to get it, even if it means risking his life in a building full of monsters.

Operation: Wildfire. Deliver a batch of vaccine to two army camps. For Alex and his friends, the task sounds simple. But in a zombie apocalypse, even the simplest tasks are dangerous.

When Alex receives a distress call from a group of soldiers being attacked by zombies, he wants to help. But when he and Sam arrive at the location of the attack, they're too late to do anything. All they find are dead bodies, dismembered zombies, and an army Land Rover. But inside the Land Rover is an item that was en route to a mysterious destination known only as "Bunker 53." Close examination of the item and its accompanying documents reveals its importance. And also the fact that some people are willing to kill to stop it reaching its destination.

Alex and a ragtag group of soldiers set down on an isolated island and begin to build a base. A lack of resources means that everyone is going to have to risk their life to gather the essentials needed for survival. Raiding parties are sent on missions deep into the heart of zombie territory. Some will return, while others will be lost forever to the hoards of undead that roam the mainland.