David, a struggling comedy writer fresh off from breaking up with his boyfriend, moves from New York City to Sacramento to help his sick mother. Living with his conservative father and much-younger sisters for the first time in ten years, he feels like a stranger in his childhood home. As his mother’s health declines, David frantically tries to extract meaning from this horrible experience and convince everyone (including himself) that he's "doing okay.”

After a virus of epic proportions overwhelms the planet—with more infected than uninfected—humanity is losing its grip on survival and its only hope is finding a cure and keeping the infected contained. Lauren, a doctor, arrives in Los Angeles with her crack team to lead the hunt for uncontaminated civilian survivors, but nothing can prepare them for the blood-soaked mayhem they witness as they head into the Californian streets where everything is considered a trap.