The Lone Piners head to the Yorkshire Moors where Harriet's grandfather is thinking of buying an antiques shop.  The old abandoned mineshaft on the property is attracting a lot of interest.  The Lone Piners find out why.

Newnes (1962)
Children's Book Club (1962)
Armada (1969)
Collins (1972)
Armada (1974)
Jade (1990)
Swift (1992)