Sam the dog and her friends Jennie and Beth find an old diary while on vacation at Sagawa Lake, which tells of a monster living underneath the lake's surface.
- Genre: Juvenile Fiction
- Subgenre: Comics + Graphic Novels / General, Animals / Dogs, Mysteries + Detective Stories, General
- Age: 9-12 years
- Publisher: Kids Can Pr
- Pages: 96
- Language: English
- Format: paperback
- Release Date: August 1, 2009
- Date Published: August 1, 2009
- Author: Mary Labatt
- Illustrator: Jo Rioux