Mikey and his friends are back in the Coreland, a world of tunnels, caves, magic and mayhem-deep beneath the city of Dublin.They've been summoned to use their brains and bravery to help the dwellers who live there.Strange noises suggest the threat of new and dangerous enemies, powerful enough to destroy the dwellers' very existence. The children have solved problems such as these before so there should be nothing to worry about-they work well as a team and Mikey has special powers.Alas, everything is not what it seems.Can they make the right decision, and in the face of danger keep their wits about them and save the day?