Book 1

The Diamond War

by Zilpha Keatley Snyder

Published 1 January 1995

Book 2

The Box and the Bone

by Zilpha Keatley Snyder

Published 1 January 1995
While building a clubhouse, the boys uncover a buried treasure, only to have it disappear later that night.

Book 3

Ghost Invasion

by Zilpha Keatley Snyder

Published 1 January 1995

Book 4

Secret Weapons

by Zilpha Keatley Snyder

Published 1 January 1995