Drug lord Alonso Marroquin is about to be extradited to the US, but an elite police unit, the DEA, the corrupt prison warden and a rival cartel all have other plans for him. Across the border, on a secret US military base, a secret experiment yields an unexpectedly dangerous result.

When Marroquin reunites with his son Lucas, he realizes that being a father is more difficult than running a criminal empire. Becerril and his elite unit realize they have underestimated their opponent. The effects of the US Army secret experiment keep spreading.

Snowman's plans to expand his experiments take an unexpected turn. Despite being fired and threatened, Lilia decides to keep going and interview the world's most wanted fugitive. DEA agent Taft breaks the chain of command and sets out on a personal quest. Meanwhile, Lucas disobeys his father's orders.

The zombie army recruits new members. Marroquin discovers that one of his men is a traitor, and a new danger hunts Lucas, who realizes that something strange is happening. Becerril gets closer to his human enemies.

When Snowman's experiments on an infected human fail, Murdoch agrees to get more human subjects. Agent Taft discovers a clue about Marroquin. Lilia escapes from an enemy thanks to Davila's help.

A zombie is tormented by his human memories. A secret mission ends badly when the US Army Rangers face an enemy that seems to be bulletproof. Valencia must break an oath. Romeo is hunted by his own past, and Chainsaw uses his abilities to capture a monster.

Murdoch takes extreme measures to contain the crisis, but Snowman has other plans. Davila and Lilia face an unexpected ambush. Lucas's attempts to save an old friend put him in grave danger, and Marroquin realizes that his enemies have found him.

An epic apocalyptic battle puts everyone to the test and old enemies must become allies. Outnumbered by the US Army, the zombies show a surprising intelligence. Marroquin must attempt another amazing escape.