"Join Us" follows four families as they leave a controlling and abusive church in South Carolina and come to realize that they have been members of a cult. The film documents them intimately as they enter the only accredited live-in cult treatment facility in the world. At Wellspring, they learn how they were brainwashed to give up control of their lives to the Pastor and his wife, allowing their children to undergo severe abuse to make heaven. As they emerge from the safety of the treatment facility, the ex-cult members return to their homes to bring the Pastor to justice and struggle to build normal lives. The film also gives voice to the cult leader and his wife, as they struggle to cope with the betrayal of their church family and rebuild their congregation.