The Three Investigators #23 Invisible Dog and #24 Death Trap Mine

In the Three Investigators #22, The Mystery of the Invisible Dog, the boys are hired to help Fenton Prentice, who has a mysterious intruder in his apartment.  Prentice sometimes spots the intruder, who appears as a shadowy figure.  Shortly after the boys begin their investigation, a valuable crystal statue of a dog is stolen from Prentice. 

This book is set in late December while the boys are on break from school.

The solution to the mystery of the missing crystal dog is quite ingenious. 

The books written by M. V. Carey usually have some aspect of the occult woven into the story, although typically, the books are written in such a way that the reader could come up with a logical explanation for the events that does not involve the supernatural.  This book leaves no room for doubt.  One of the characters experiences astral projection while he sleeps, and the story is written so as no other explanation is possible.

This is a very engaging and entertaining story.  The book is outstanding.

In the Three Investigators #24, The Mystery of Death Trap Mine, Allie Jamison tricks the boys into helping her solve another mystery.  Allie is staying with her uncle in New Mexico, and she is convinced that their neighbor, Thurgood, is up to something.  The boys travel to New Mexico to stay with Allie and her uncle. 

Allie also appears in The Mystery of the Singing Serpent when she blackmails the boys into helping her solve a mystery.  Allie is a likeable character who adds an interesting dimension to both stories in which she appears.  Allie could get old if she were overused, but I wouldn't have minded seeing her in one or two other books.

This is another excellent book.