Merdyn the Wild is from the Dark Ages. He's the world's greatest Warlock (don't call him a wizard), banished to the 21st century for bad behaviour, and he's about to create a whole load of trouble for Rose, aged 12. Rose is a totally ordinary girl, on a mission to mend her broken family. Bubbles is Rose's guinea pig. He just poos a lot. When Rose bumps into Merdyn and discovers what he is, she quickly realises that he could be just what she needs. Rose agrees to help Merdyn navigate the confusing ways of the modern world (things like: the lidded bowl in the bathroom is NOT a sink, it's a TOILET, so definitely DON'T wash your face in it) if Merdyn gives her a spell to fix her family in return. Now they just need to hide him in the shed without Rose's mum noticing, track down Merdyn's magic staff and find a way to send Merdyn back through time to the Dark Ages. What could possibly go wrong...?

In an exclusive for World Book Day, Bubbles the guinea pig shares his thoughts about wizards, magical adventures, his owner, Rose, dogs, pooing - and food. Mostly food. This is a story about me, Bubbles. Find out how Merdyn the Wild, a wizard from the Dark Ages, landed in my life and distracted my owner, Rose, with magic and adventures. My top five people: 1) Rose, because she feeds me 2) Merdyn, because he cast a spell so that Rose could understand me 3) Mum, because she sometimes feeds me 4) Um. Not Rose's brother, Kris, because he ignores me 5) The owner of the pet food store - mmm, food... A companion volume to The Wizard in My Shed and The Warrior in My Wardrobe. Brilliantly illustrated by Claire Powell.

Merdyn is the greatest wizard of the Dark Ages. Obviously. Rose is his 21st-century descendent. Lucky her. And Vanheldon the vandal warrior is FURIOUS! After all, last time they met, Merdyn turned his army to stone. Seeking revenge, Vanheldon comes up with a way to kidnap Rose and transport her back to Dark Ages Transylvania, set on luring Merdyn into a terrible trap. Except - whoops! - his magical minion kidnaps Rose's teenage brother Kris instead. Rose, Merdyn and Bubbles the guinea pig must team up to save the day. But can they rescue Kris without creating historical mayhem? Will Rose's wizard ancestor even remember her? (And want to help them?) And will Bubbles ever stop pooing?