security officer Decker (Jon Bernthal), and Atlas executive Kahn (Bill Paxton) - attempt to evacuate, but both of their rescue helicopters are destroyed. The four survivors mount a last stand against the zombie horde, but are eventually overwhelmed. However, they are rescued by Atlas forces, who then take them to an urban facility, for medical treatment. When the four survivors recover, they are thrown into another battle against the infected, ensuring the survival of not only themselves but also innocent citizens trapped in the vicinity. Eventually, the group is rescued by Sentinel Task Force operatives, but their leader, Captain Lennox (Bruce Campbell), claims that Oz is the source of the zombie infection. Lennox executes Oz and has Lilith, Decker and Kahn injected with anesthetic. However, Atlas forces ambush them and reclaim the ex-Atlas employees. Sentinel tracks them down, leading them to an Atlas aircraft carrier in the middle of the ocean. Oz, however, begins to reanimate while being transported on one of the Sentinel's transports. Upon arrival within the carrier, Lennox locates the three Atlas survivors and leads them in battle against the combined forces of the zombies and Atlas soldiers. Lennox reveals to the other three that Oz was once part of Sentinel, and that he was present at the prison when Atlas released the Manticore bomb, making him one of the first people infected. He also claims that Oz was planted in Kahn's facility by Atlas in order to start the zombie outbreak. The group decides to sink the carrier to the bottom of the ocean, in order to prevent the infection from spreading. They set the ship to self-destruct, but before they can extract in an emergency pod, they briefly encounter Oz, now fully zombified while retaining his intelligence. The group escapes and decides that Oz must be eliminated, and head to a nearby Atlas underwater survival facility, the Trident Retreat. Oz, however, has already arrived at the facility and murdered all Atlas employees within the base. The group bands together for one final battle against the undead horde, including Oz himself. After undertaking various challenges set by Oz, they are teleported into a digital representation of Oz's memory, where Kahn, Lilith and Decker learn the truth: while they are immune to the Manticore virus' effect, they can be used as a cure for the infection, unlike Oz. Having finished all of Oz's challenges, the group finally