Hammer catches up with an old friend, Kate. As she is leaving him a pickpocket steals her wallet but Hammer is mystified when she doesn't want to speak to the police. Later he has a meeting with her but they are run over by a car but Hammer still doesn't know why. Further investigation shows that Kate is an escort and her clients are diplomats that are being blackmailed - but why?. As the bodies mount up Hammer finds that international subterfuge is involved.