Hidden Fortress is the 13th episode of the series, and part 1 of the season 1 finale.
Plot
A foe known as the "Supreme Destructor" is causing havoc. He apparently killed Jinmay. The Hyperforce travel to outer space in search of the villain. He's revealed to be Mandarin, working for the Skeleton King. The monkeys are busy trying to escape through an obstacle course, so they can't help Chiro beat him. Antauri sends Chiro a message to use the Power Primate to defeat Mandarin. Then, Sakko appears, also working for Skeleton King. One can only hope that the Power Primate's force will defeat all three of these evil fiends.