Rex Carver is a private-eye based in London, but his work can take him far from there. This case leads him to Ireland and to France, whilst he is trying to find a man left a legacy by an aunt. The man is involved with a large haul of diamonds, and Rex has to deal with people about to trade these millions of dollars worth of stolen diamonds for heroin and opium. Two of these people are attractive twin Chinese sisters Suma and Lian, agents of the People's Republic of China...