“The Hand on the Wall” is the last book in the trilogy of “Truly Devious” novels by Maureen Johnson. Once begun, this series of mysteries is addictive. The setting, a prep school in the mountains of Vermont, is perfect for a murder mystery, and in this brilliant trilogy, there are multiple murders taking place over almost a century.

In the first novel, the main character, Stevie Bell, is introduced. She is obsessed with mysteries and especially the long-unsolved mystery of what happened to Alice Ellingham, the kidnapped daughter of millionaire Albert Ellingham and his wife Iris. Ellingham Academy in an isolated area in the mountains of Vermont offers Stevie the best chance to attempt to solve the mystery, so she applies and is accepted into the private school. The first two novels lay the groundwork for this third book, and as of the start of this book, there have been three recent deaths — staged to appear accidental — and Stevie is determined to solve what she believes are the recent murders, in addition to the mystery of the long ago disappearance of Alice Ellingham and the death of her mother. Two of the recent deaths were of students who lived in Stevie’s dorm, and the third death was a faculty member with whom Stevie worked.

Stevie has reason to believe that the murders are connected to a mysterious codicil to Ellingham’s will which may or may not exist. At the start of this novel, Stevie’s friend and — maybe? — boyfriend David has disappeared after a shocking video emerged of his being beaten. No one knows where he is, and David’s situation is further complicated because of the character of his father. Only Stevie knows that the man is a despicable politician who is bent on achieving higher office and will do anything to get there.

There’s lots of action and also lots of reflection as Stevie works to prove her ability as detective extraordinaire. She takes risks but also plods through documents to get evidence. When there is another, albeit not fatal, accident, and a blizzard is approaching, the school is evacuated for the safety of the students. But Stevie and her friends stay at the school, hidden, so that they can help another friend. This respite also gives Stevie the time to try to finally put together all the pieces and solve all the mysteries.

There are many questions to be answered and unsolved mysteries to be solved, and Johnson puts it all together masterfully in this last book. The alternating time period narratives, the clues, the third person present narrative that still allows the reader to understand Stevie’s thought processes and motivations all serve to keep the pages turning as the reader is drawn into the puzzle to the final very satisfying conclusion. Read “Truly Devious” and “The Vanishing Stair,” and the stand alone mystery “The Box in the Woods.”

Please note: This review is based on the final, hardcover book provided by Katherine Tegen Books, the publisher, for review purposes.