The Jönsson Gang in Mallorca.

Vanheden and Dynamit-Harry, together with Harry's fiancée Doris, are in Mallorca while Sickan is still in Stockholm. However, Wall-Enberg talks him into doing a break-in at Las Palmas cathedral in Mallorca. Once persuaded, he can't resist the temptation and travels to Mallorca as well. However, Wall-Enberg obviously can't be trusted. Sickan is framed, caught and put in jail. While being escorted home to Sweden again, Vanheden and Harry sets up a plan to break him free. Sickan, once free, wants payback. The gang discover that an antiques dealer called Germann has something to do with the whole thing and that she's also collaborating with Wall-Enberg. The gang then decide to take a closer look at her and her antiques and they discover that there's a heist being planned against the cathedral in Palma.