Clan chieftain Finn McCool has disappeared and his men are under attack. That's the devastating news that greets Jack when he's shaken awake late one night at home by bloodied and battle-worn warrior Cormac.

Jack knows it's down to him as Prince of Tara to rescue Finn and save the clan itself. But first things first; Jack has to get both he and the bedraggled warrior out of the family home and back to Eireann without the rest of his family finding out.

That's not so easy when Dad's got the Midnight Munchies and Nan suddenly decides to start poking about. Some seriously swift talking, a surprise intervention and the mysterious rubifelis help Jack and Cormac travel in the magical trunk from Jack's attic back in time to the place they hope to find Finn.

But when the trunk is opened, it's revealed that they've ended up...where? Not the Forest of Roann from where they assume Eireann's evil High King Goll has kidnapped Finn but somewhere else entirely.

At first glance, it looks as if they've landed in paradise but Jack and Cormac soon discover that the steamy heat and dense jungle filled with strange sounds, strange creatures and even stranger - and deadly - plants, hide a land that's rife with unseen dangers and inhabitants who would do them harm.