The Boston Druid and the Wizard

The story opens as Brian is caught by a Troll and through a series of events, unintentionally ends up as Champion to the Faerie Queen and betrothed to Maedbh, a 13th century Celtic teenage princess.
Brian is 16 years old and lives with his mom and dad and older brother in a deprived part of modern Dublin City Ireland. He must live his normal life in parallel to his role in Otherworld.
At school Brian gets into a fight with Robbo, the school bully, a grandson of the local gangster. Brian also runs a band but his brother, as band manager, is using the band as cover to make deliveries for Polar Bear, the local gangster and drug lord.
As Champion Brian is required to do battle with the Engapmahc. And when the Engapmahc captures the Faerie Queen, Brian must undertake the rescue.

At the same time, Druid Lochlain is on the run in Boston USA but is located by the Drimnagh Witches. How does the Faerie Queen end up as his prisoner whilst still the prisoner of the Engapmahc? And why does Lochlain call upon the dark forces of Underworld to invade Otherworld? How does Brian, the Queen's Champion, resolve this?
Brian's normal life complicates when he has to bring Maedbh home. Also Robbo's grandfather decides that Brian should be killed as Robbo's first hit as a trainee gangster.
How will Brian handle the demands of both a normal teenage life and double jobbing as Champion to the Faerie Queen of Otherworld?