El Santo joins an expedition to explore the ancient ruins of native Opalche Indians in The Vengeance of the Mummy. Along for the trip are the absent-minded Professor Jimenez and Sergio the Hunter, a native Indian guide with his grandson, and a few friends. The group finds the mummified tomb of the Opalche Indian warrior Nonoc. Entering the tomb they find a scroll placing a curse upon any and all who enter the eternal resting place of Nonoc. When people start disappearing, Santo must act quickly and save his friends from the mummy's wrath.

Not as boring as Santo vs. Cazadores de Cabezas, the trick ending is still a letdown.