For the first time ever, Rico has a friend coming over for a sleepover! After weeks of not seeing each other, Rico and Oskar are reunited again and start their adventure with the weekly bingo at the retirement home. But although Rico's mother Tanja even wins two handbags, Oskar seems suspiciously grumpy and Tanja oddly sad. On top of things Oskar's dad leaves a bag in front of the door because he needs some distance from his son. So much heart affliction is too much for Rico! When Oskar finally tells Rico that Tanja was cheating at bingo the other night and that those ugly handbags she wins all the time are really expensive leather bags, Rico refuses to accept that his mother could be a crook. Ellie Wandback, the bingo host, must be blackmailing her. Rico and Oskar seek help from the sprightly pensioner Mr. van Scherten and together they try to find out what is going on. Not everything goes as planned, but in the end the two young detectives shall discover more than just the truth about the bingo-cheat and the handbags.