The Hidden Beast is the twelfth novel in the Spooksville series. It marks the third appearance of Bryce Poole, who becomes a main protagonist and is present throughout the final twelve books. The summary on the back cover reads:

"The Dragon was not from any story they had ever read. There are more troubles in Spooksville. A dragon has appeared out of the nowhere and it is looking for its treasure. In fact, it intends to destroy the entire town unless its jewels and gold are returned immediately. The only trouble is that Adam and his friends don't know where this treasure is. Worse, the creature is rather hotheaded and won't listen to reason. It is a fire-breathing dragon, and soon it is laying waste to all that stands in its way. Even kids - it doesn't mind burning them to ash. Soon Adam and his friends are fighting for their lives.

It was published in 1996 by Pocket Books, a subdivision of Simon & Schuster Inc, under the A Minstrel Book division.