A timid and socially awkward accountant, Casey, is emotionally shattered after a brutal mugging leaves him hospitalized. Struggling to regain his confidence, he decides to join a local karate dojo, seeking empowerment and protection. Under the enigmatic leadership of the dojo's charismatic sensei, Casey delves deeper into the world of martial arts. Initially, he begins to find a sense of belonging and renewed strength among the fellow practitioners, especially admiring the advanced skills of Anna, the sole female student. The sensei's unconventional philosophy and intense training methods challenge Casey to confront his fears and insecurities.

As Casey progresses in his training, he becomes increasingly committed, but he soon uncovers a darker and more sinister side to the dojo's practices. The strict hierarchy within the dojo and the sensei's manipulative control lead Casey into morally ambiguous situations that test his values and judgment. As his dedication grows, so does the unpredictability of the sensei’s intentions, pushing Casey into a dangerous spiral where he must determine how far he is willing to go to assert himself.