Returning by car from a vacation at the Boy Scout Camp in New Mexico, Hap Livingston and four of his Boy Scout Explorers camp overnight at the Rocking Horse Motel. The boys meet Stony, an old prospector with intriguing tales of a map locating a secret gold mine. At first the Explorers doubt the old prospector's story, but when he is attacked and left for dead during the night, the boys begin to suspect that his story is true.

Stony is taken to the hospital, where he tells the group of his lucky strike in Colorado and how he was blamed for the mysterious murder of his partner. Stony requests that the Explorers find his gold and give it to the son of his partner. The Explorers obtain Stony's map but are confronted by Jarrett Walz, owner of the Rocking Horse Motel. Walz hopes to use the map to find the gold for himself and will stop at nothing to achieve this goal.

The Explorers travel to Colorado to find the heir to the mine, accompanied by their unwelcome companion, Jarrett Walz. The Explorers face great danger and share many adventures before they finally succeed in their search for the lost gold.