Quinnan finds the body of Dennis Quigley, a man who has died of a heart attack in his car. Whilst delivering the man's personal effects to his wife, Quinnan is mortified to find they include a gift to the man's mistress, a woman named Alice. Trying to do a good deed, Quinnan resolves to deliver the gift to its intended recipient, and manages to locate Alice and give her the gift. However, things become much more complicated when his wife Jenny discovers the gift and thinks he's having an affair, while CID discover that the dead man is wanted by Interpol for diamond smuggling. Suspecting the package that Quinnan handed over may well be a shipment of uncut diamonds smuggled in from Antwerp, Cullen is left dismayed after realising the evidence has been lost.