Book 3 of 21 in the bestselling standalone middle grade mystery series!
Collect All 21 Full Length Novels and 15 Short Stories
★★★★★ Over 15,000 reviews/ratings on Amazon
Are you up for a thrilling adventure?
While camping in Wales, it doesn’t take long for the Mystery Kids to stumble across a long-lost tunnel that leads to a valley full of secrets.
Follow the children as they are imprisoned in an old farmhouse, discover a hidden cave, sabotage a plane, rescue a missing man, undertake a perilous climb, and more!
This adventure novel is set in 1950’s Britain and will suit anyone who enjoys Nancy Drew, the Hardy Boys or the Famous Five.
