Dr. Harriman, a scientist who used to cut corners with building materials, and now an inmate at the Lunar Penitentiary is broken out by Doc Terror, who wants to use his knowledge of . Rex and John investigate Harriman's daughter Alexis, at her research lab. Terror then attacks the lab, and despite the Centurions' efforts, succeeds in stealing Alexis' new sonic ray. Suspecting Terror had an insider, Rex discovers that Alexis herself is helping him and her father in getting revenge on the World Council of Scientists. John discovers that Terror intends to use the sonic ray to destroy a new dam, but is captured by Hacker. John must figure out a way of escaping and warning the other Centurions before Terror can use the ray to destroy the dam. Science Lesson: Agricultural methods by Jake.