Eleven of the twelve passengers in a boat plane making a trip across Italy watch the twelfth head to the front of the plane and lock himself in the tiny toilet cubicle. Thirty minutes later, when he has not emerged, someone else impatiently bangs on the door and insists the current occupant allows others to avail themselves of the conveniences. No reply is forthcoming. When the door is broken down, having been bolted in the expected manner, there is no sign of the passenger, nor any exit large enough to admit his egress (he was rather too, ahem, corpulent to have slipped through the skylight). So…where is he? And, more to the point, how did he get there?