The Jönsson Gang in Mallorca

Vanheden and Dynamit-Harry, along with Harry's fiancée Doris, are in Mallorca while Sickan remains in Stockholm. Wall-Enberg persuades him to attempt a break-in at Las Palmas cathedral on the island. Once persuaded, the temptation proves irresistible, and Sickan travels to Mallorca as well. Yet Wall-Enberg cannot be trusted. Sickan is framed, captured, and imprisoned. While being escorted home to Sweden, Vanheden and Harry hatch a plan to break him free. Sickan, once free, seeks payback. The gang discovers that an antiques dealer named Germann has a hand in the whole affair and that she's collaborating with Wall-Enberg. The gang then decide to take a closer look at her and her antiques, and they discover that a heist against the cathedral in Palma is being planned.