Billy is trying to stay awake so the SCARY creatures of the dark won't come. But then he hears a squeaky little voice and notices some tiny purple footprints. Not only that, SOMETHING has ATTACKED his cheese sandwich. What could it be? Does Billy dare find out?

Billy's pet Mini Monsters really want to go to school with him. Billy really doesn't want them to come. He's got enough trouble with the school bully, Basil Brown. But perhaps having MONSTERS around will be more helpful than Billy imagines ...

Billy hates swimming. It is cold and wet and horrible. And just when Billy thinks things cannot get any worse, his pet Mini Monsters turn up at his swimming lesson and make one very big SPLASH.

It's Halloween and Billy can't wait for the spooky party. But when he arrives, he discovers Sparkle-Boogey in the apple bobbing, Trumpet in a pumpkin and Gloop playing "Guess the body part." Can Billy get his Monsters back? Or will it be up to Peep to save Halloween

The mini-monsters cause chaos at Christmas. Can they work together to tidy up? It's nearly Christmas and Billy and Ruby are feeling very excited. Billy has asked Santa to bring presents for his Mini Monsters and they're very excited too, until they try to help with the decorating and bring down the entire Christmas tree. Now the baubles are broken, the fairy is squashed and Billy's mother is feeling sad. Can the Mini Monsters make Christmas right...

Billy's learning how to take care of the planet, and the mini monsters want to help too... so they join the school trip to a recycling centre, only to fall into one of the recycling machines. Can Billy and his best friend, Ash, rescue the mini monsters in time?