Picking up just a few short minutes after the first film left off, Jaume Balagueró and Paco Plaza's adrenalized action horror sequel follows a heavily armed SWAT team and a tight-lipped medical officer as they venture into the quarantined tenement building to uncover the origins of the bizarre outbreak. Their helmet-mounted cameras capturing every nerve-shredding moment of the mission, the team must fight for their lives when they're beset by rampaging victims of the demonic virus. Now, with each new attack, the infection grows, and the horde gains power. Should the virus somehow manage to spread outside, the result would be a disaster of apocalyptic proportions. But there's still hope; the medical officer seems to know something about this infection that he hasn't yet shared with the others. Somewhere in the building, an antidote to the virus waits to be discovered. But in order to find it, these terrified soldiers will have to fight their way through a true hell on Earth.