After being left for dead by some shady business clients over some diamonds in Africa years ago, Robert Griffin (John Hall) returns to his native England Having survived against terrible odds, the revenge-minded Griffin returns to England where he Dr. Drury (John Carradine), who is testing out new invisibility formula. Vengeance on his mind, Griffin consents to be a guinea pig, allowing him to go after those who did him wrong. Unfortunately, there are a few unpleasant side effects. Serial director Forde Beebe directs Hall, who plays a different invisible character than the one he portrayed two years earlier in THE INVISIBLE AGENT.