Book 1
The Mystery of the Whistling Caves
Helen Moss & Leo Hartas
Book 2
The Mystery of the Midnight Ghost
Helen Moss & Leo Hartas
Book 3
The Mystery of the Hidden Gold
Helen Moss & Leo Hartas
Book 4
The Mystery of the Missing Masterpiece
Helen Moss & Leo Hartas
Book 5
The Mystery of the Cursed Ruby
Helen Moss & Leo Hartas
Book 6
The Mystery of the Vanishing Skeleton
Helen Moss & Leo Hartas
Book 7
The Mystery of the Dinosaur Discovery
Helen Moss & Leo Hartas
Book 8
The Mystery of the Drowning Man
Helen Moss & Leo Hartas
Book 9
The Mystery of the Smugglers' Wreck
Helen Moss & Leo Hartas
Book 10
The Mystery of the Invisible Spy
Helen Moss & Leo Hartas