Uncle Fax is too fat. Fix and Foxi's diet plans are at least as ingenious as Uncle Fax's cheating. At Fix and Foxi and Lupo a carrier pigeon lands with a message. Someone needs help urgently. The friends follow the pigeon to an old tower. There sits a girl who is guarded by a nasty monster. Granny Eusebia's beautiful piano playing attracts the rather unmusical Phantom of Fuchsburg, who urgently wants her to be a piano teacher. He kidnaps Granny into the underground sewer system where he lives with his crocodile and doesn't want to release her until he can play just as well as Granny. During a heavy rain shower the Pepperkorns notice a leak in the roof. At first it's only a few drops, then almost a waterfall is streaming into the apartment. The repair attempts of Papa and Lucky fail miserably. Mum invents a water recycling system.