The death of Professor Goodman is officially recorded as a tragic accident, but at the inquest, no mention is made of his latest discovery - a miraculous new formula for manufacturing flawless diamonds at negligible cost, which strikes Captain Hugh " Bulldog " Drummond as rather strange . His suspicions are further aroused when he spots a member of the Metropolitan Diamond Syndicate at the inquest . Gradually, he untangles a sinister plot of greed...