A ride on an old steam train catapults three children into a dark and mysterious adventure. Becky, Daniel and Luke find themselves at the centre of a riddle that begins with the disappearing man. Through a series of discoveries and events involving secret tunnels, old fairground horses and weird happenings in the dark, they become embroiled in a deadly puzzle that threatens their very lives. Why is the old mansion suddenly bathed in a blinding blue light and is the boy they meet there a friend or an enemy? The children need all their courage to complete the challenge and along the way they discover that sometimes four legs are best