The trolley carrying Mary and Harriet hurtled into the tunnel. Their screams echoed back deafeningly from the dripping walls. Where were they heading? The wheels screeched along the rails of the track at an ever- increasing speed, and the two girls clung together in terror as they rushed helplessly into the unknown...
Gripped by fear, Harriet and Mary head towards the thrilling climax of one of the most exciting mysteries the Lone Piners have ever tackled.
