A suitcase is found abandoned at Heathrow Airport, and panic ensues, but it is soon discovered to be no terrorist threat. Inside is the naked body of Sofia Petrenko, a high-class prostitute, who has been strangled to death. The suitcase is traced to Vitali Malikov, a Ukrainian billionaire who admits to hiring Sofia's services, but he claims she was alive when she left him and that the case was a gift. D.C.S. Walker arrests Malikov on suspicion of murder, but later has to release him, and soon realises he has become a pawn in a much bigger game.

Another working girl, Maryna, is put on trial for assaulting Malikov. She claims self-defence but the trial is mishandled and walker is even more adamant then before that he will get the Ukrainian. Roisin, however, believes that his obsession with Malikov is blinding him to the identity of the real killer of Sonya and takes the investigation down a different route.