In their first great adventure, Huckleberry Finn, Tom Sawyer, and Becky Thatcher visit a valley where they witness the theft of a powerful gem from an idol that the natives worship. The boys wind up becoming responsible for its safe return after being initially accused of stealing it. With Becky as the natives' hostage, they have a short time to get the gem back before she's sacrificed. Will Tom and Huck overcome the odds against the thugs and save Becky in time?