The UCOS team investigate the murder of a private investigator. The victim was stabbed through the heart in a suspect robbery. The team believe the answers are in the victims last three cases however it will take the whole team's expertise and instincts to be able to crack the case along with a mysterious notebook. UCOS believe the movements of a rare collectable stamp, The Russian Cousin, could hold the key to the investigation- will UCOS be able to track it down? Elsewhere Steve rents his flat out to a pair of demanding Italians. Also Ted is fearful of a trip to the doctors after concerns of his own mortality.