The Magicians' and Enchanters' Convention is taking place and magicians, wizards and enchanters from all over the Hidden and Obvious Worlds have flocked to Owlchurch. But when the valuable golden prizes donated by the Klint-king are stolen, Thomas and his friends start to investigate. The mysterious Brock Blackbeard is high on their list of suspects, but when they're kidnapped by a gang of ruthless thieves it appears that they've stumbled upon a much more elaborate and scary plot ...