Andy and Terry have expanded their treehouse! There are now thirteen brand-new storeys, including a dodgem-car rink, a skate ramp, a mud-fighting arena, an antigravity chamber, an ice-cream parlour with seventy-eight flavours run by an ice-cream-serving robot called Edward Scooperhands, and the Maze of Doom - a maze so complicated that nobody who has gone in has ever come out again . . . well, not yet anyway . . .