For Otis, this was a sleepover to remember - if only he could! When dorky, unpopular 11-yr-old Otis wakes up in the morning at a sleepover birthday party, he's in for a shock. At the marquee where the sleepover took place, it's a scene of carnage and mayhem: there's a donkey drinking at the chocolate fountain, a huge inflatable helium sausage looms above, doves everywhere, one of the kids has a tattoo, and there's a suitcase of bratwurst on the floor! But what's weirdest of all, neither Otis nor the other kids can remember what happened! The party was in the back garden of popular kid Rocco Rococo's huge house, and Otis was only there because his mum forced an invitation. Otis realizes that makes him Prime Suspectfor causing the mess, and he needs to clear his name. Meanwhile, Rocco just needs to keep his parents from finding out! So while everyone else makes a befuddled exit, Otis and Rocco reluctantly team upto hide the evidence. They decide to retrace their steps in the hope of solving the mystery...