The Mask of Mystery

Lex Luthor uses a clumsy fan of the Superfriends to destroy them. The fan Sidney Wanamaker, a school mate of Firestorm's alter-ego, Ronald Raymond, creates his own secret identity...called Captain Mystery. He taps into the Hall of Justice files and shows up to help the Superfriends but winds up causing more harm than good. Luthor notices this and kidnaps Captain Mystery and intends on using him in his plot. It's up to the Superfriends to rescue Captain Mystery and capture Lex Luthor.