Book of Legends:
What if all the stories were real?, The
Sir Lenny Henry

Bran and Fran love living with their mum, who is the storyteller at the Once Upon a Wow bookstore in their small Midlands town. But when mum goes missing and her stories turn out to be a portal to another world, they're going to have a huge, magical adventure on their hands.Luckily, they have Wilma, the Wizard's Wife, and Zack, the wisecracking Zebracorn, to help them on their journey. And they're going to need help because there are evil princes, mud monsters and Viking armies all standing in their way...