In this dark tale of revenge, Bruce Lee "returns" as Billy Lo, whose best friend Chin Ku dies of a sudden illness. But suspicion of foul play arises when a gang tries to steal Ku's coffin at the funeral using a helicopter. When Lo's younger brother Lo hears about the incident, he leaves his Buddhist master to investigate the truth. His trail soon leads him to the Castle of Death, the last place Chin Ku was seen alive. There, he meets and befriends an unlikely ally--a cruel and merciless martial arts expert who is also the tower's master. But when the master dies under mysterious circumstances, Lo ends up dueling with someone far more terrifying.