Three naïve guys, in their 20s, drive from Illinois to LA. A sleazy real-estate agent gives them a great deal on a house in the Hollywood Hills. The night they arrive, a solitary Mexican, who speaks only Spanish, tries to warn them that the place is possessed by Satan. They don't understand him, move in, and plan a party after they meet Lucy, their gorgeous neighbor from down the hill. An old friend of theirs, studying to be a priest, joins them. In the basement is a portal to Hell, so at the party, guests meet their end in various ways. Lucy and her friends may not be who the lads think. Is there any hope for these innocents? Maybe their neutered dog can help.

Season three reveals an origin story set centuries earlier, while continuing the saga of a dystopian society of 10,000 people living underground under mysterious circumstances. In the present, Juliette Nichols survives her forced "cleaning" but returns with memory loss as the silo recovers from rebellion and faces a dangerous new threat. Meanwhile, in the "Before Times," journalist Helen Drew and Congressman Daniel Keene uncover a conspiracy that pulls them into a chain of events with catastrophic, irreversible consequences.