Two merry widows, Tilly and Elsa, are on a grief cruise to celebrate the lives of their departed loved ones. When the ship docks in Cape Verde, the two of them join a small group going to visit a shrine to pay their respects to those they have lost. When Tilly is found murdered, Jack and Kate investigate to uncover the killer's identity.

In Ibiza, two old flames, Alex and Lucia, reunite in the nightclub where they first kissed some twenty years previously. Alex is on a lads holiday with his lairy mate Gary, and Lucia now co-owns the club. But then Lucia's slimy business associate, Rico, is murdered - pushed off the balcony of the club. Jack and Kate are on the case.

Various suspects emerge. Lucia herself seems to have ample motive for wanting Rico out of the picture. Also in the frame are Carmen Rivera, a local mafia boss who is trying to force Lucia out of the club, as well as her henchman Paco. In an effort to protect Lucia, Alex himself actually turns himself in, confessing to the crime.

Meanwhile, in the wake of learning about Marlowe's illness, Jack remains at odds with Kate, but he can't stay mad with her for long and the pair eventually reach a new understanding. Also, Jamil prepares for his big audition to join the Ents team.