An elderly couple approach him hoping that he'll be able to help reunite them with their daughter who has "fallen away". There's none of this redemption nonsense, the deprogrammer, just needs their money.
With the assistance of some comically inept goons, he kidnaps the daughter and takes her to a motel that's seedy even by his standards, and begins the normalization process.
Rather than a battle of wills between cult-breaker and cultee, it becomes more a battle of realities, her one of perceived enlightenment/ascendancy verses his more tangible, but problematic, one of emotionally cold biological families and intimidating debt collectors.
As with almost every film ever made, things may not be as they seem and there's a (fairly good) twist.
Look at all that nonsense, typing stuff like a grown up without once mentioning arses or pubes.