On a summer holiday in Wales, Portia and Ben find a mysterious door set in a bramble hedge in the middle of a forest. It is a portal to the Otherworld and should never be opened, but how are they supposed to know that? After all, the old stories about the wonders and dangers of the Otherworld have long been forgotten...

For Robin Goodfellow, the man with the fox shadow, the children are his last chance to open the portal and finally return home. But for everyone else, the door spells great danger. This thrilling fantasy adventure immerses young readers deep in the world of British myths and legends.