Thundarr, Ookla, and Ariel are in pursuit of a mummy-like Janus after he and a race of hawk mutants attack villages and the train route of Tye (the former swamp urchin from "Harvest of Doom"). The group is in for a surprise when it turns out Janus is actually Gemini (the two-faced wizard from "Secret of the Black Pearl") in disguise seeking revenge on Thundarr. Tye, from "Harvest of Doom", returns as a train driving "businesswoman".