A scientist's laser shot at the Moon unleashes a "moon beast" who zooms to Earth. The beast runs rampant, eating metal ravenously. It also blasts its "organic rocket" jets into the ground. Prof finds a ship's log that tells how an alien race locked the beast up on the Moon. They also find a jar of anesthesia. When the beast attacks, the Challengers fend it back with flares. Prof duplicates the anesthesia. As the beast zooms through the sky with Rocky holding tight, Prof pitches the jug down its gullet. The Challs seal the beast in a capsule full of knockout gas and send it back to the Moon.; At Fun-Land, Madame Zaddum shows the Challengers a possible future. The Challengers are old and married (Ace to June) and their kids play "Sons of the Challengers", including "Roxy" Davis, a GIRL who tags along. The kids pursue the Flying Fishmen who raid ships. The boys ditch Roxy as a pest, but are captured. Roxy follows. The Fishmen hide in an underwater dome, a leftover movie set. The elder dads crash the place to rescue the kids and capture the crooks. They followed Roxy, smart girl! A true glimpse of the future? Or fiction? Only time will tell...