Russ Grote is scheduled to reunite with his estranged son after a decade lost to addiction and criminality. On the day before he is set to leave, Russ and his work crew are attacked by a horde of savage pigs. They take refuge atop a billboard, but the pigs, who are infected with a mysterious virus, refuse to leave. The brutish men, all ex-convicts, grow desperate and will do anything to survive. Russ believes he has left his vicious ways in the past, but revisiting them may be his only hope. Who will he be when the devil climbs?