7 books in series

Ghost Twins

Ghost Twins is a 7-book series with 7 primary works first released in 1994 with contributions by Dian Curtis Regan.

The Mystery of One Wish Pond
The Mystery on Walrus Mountain
The Missing Moose Mystery
The Mystery of the Disappearing Dogs
The Haunted Campground Mystery
The Mystery at Hanover School
The Mystery of the Haunted Castle