Professor Goodman gets tragically in avaraet and dies. So many thought, except for Captain Hugh Bulldog Drummond. He suspects that something is wrong. It turns out, his latest discovery a miraculous new formula for manufacturing flawless diamonds at negligible cost. His suspicions are even more awakened when he notices a member of the Metropolitan Diamond Syndicate during the investigation. Subsequently, the detective unravels an ominous conspiracy and begins the race for the real killer.