On an autumn day in Venice, private detective Victor Getz tries on a new mustache as a disguise when Max and Esther Hartlieb come to his door. They show him a picture of their nephews, Prosper and Boniface, who ran away from Hamburg after their mother died. They wanted to adopt five-year-old Bo and send 12-year-old Prosper to boarding school, so the boys ran away to Venice, which their mother used to tell magical stories about. Max and Esther hire Victor to find the boys. Victor is unimpressed by the heartless Hartliebs but doesn’t want the boys to remain on their own, as they have been for eight weeks. He feeds his tortoises, Lando and Paula, whom he found during another case. He tries to decide where to start looking.

Prosper and Bo came to Venice by stowing away on trains. In Venice, they had trouble finding shelter, and Bo got sick. Prosper was seeking help from a policeman when Hornet, one of the Thief Lord’s crew, found the brothers. She brought them back to the Stella, which the crew calls the Star-Palace, and promised them that the Thief Lord would look after them.