When a young labourer falls to his death at a building site, Inspector Rivera and Rex suspect foul play. They soon discover that he had been the toy boy of the rich widow who owns the site, until he had fallen in love with her daughter.

Inspector Rivera and Rex go to a charity event in a wealthy man's villa, only to become trapped in a hostage situation. A group of masked men hold the party guests hostage demanding the combination of a safe. But the host has escaped and is reluctant to give them the combination.