Out of the Gunpowder Tower into a haunted castle. But the ghost is really Willy fooling his friends, as Karl and Peter and Fritz find out when they paddle their houseboat back to the island to find him. The castle's owner shows them the weapons room and lets them try on the armor, then invites them to dine on the pike that Peter caught that afternoon. They clamber into (and over) an old curtained bed and hitch a ride home the next day--tied to the stern of an excursion steamer. In bit hold pictures, roving on the Rhine is a good time for all.