Marlon is now slightly older and is faced with the problem of how to amuse himself, having exhausted all the appeal of creating intergalactic battles with his long-suffering mum's furniture. "I wish I had someone to play with" complains Marlon, and goes off in search of companions Alligatina, Boomps-a-daisy and Basher.
He finds the friends dressed as the three Musketeers, but they're reluctant to let him join in their fun—"We'll think about it" being their refrain. Marlon persuades his mum and grumpy Granny to help him put together a dressing-up costume, but finds that his monster friends keep changing their game and he's still excluded! However, the tables are turned when Marlon's luxurious paddling pool appears in his back garden.