Welcome Back, Kotter (1975)
S03E07 The Deprogramming of Arnold Horshack
Episode Overview
Arnold finds himself drawn into a religious cult, leading Mr. Kotter and his fellow sweathogs to rally together in an effort to help him break free. They work tirelessly to remind Arnold of his old self and the joy he once radiated. After a series of heartfelt interventions, Arnold finally awakens from the cult's influence and returns to his original personality, complete with his iconic laugh, much to the relief of his friends.