Two years on from uncovering a terrifying conspiracy of rogue scientists, all Kate Maddox wants is to lead a normal life with her partner Paul and son Jack. But then a face from the past turns up, bringing chilling news. A devastating new strain of the virus that killed Kate's parents is loose in L.A. - and when a bomb rips through a hotel killing many top scientists, it becomes clear someone will do anything to stop a cure being found. While Paul goes on the hunt for answers, Kate finds herself in a secret laboratory in the heart of California, desperately seeking a way to stop the contagion. But time is running out and soon it will be too late to save their loved ones, themselves, and the world...