The Mark of...The MADMAN!
Although offered a membership with the Fantastic Four, Crystal must return to her fellow Inhumans and ask for permission to act as a member of the group. Transported to the Hidden Land by Lockjaw, an army of Alpha Primitives appear in their place, attacking Reed, Johnny and Ben.
While in the Hidden Land, Crystal is taken prisoner by Maximus who has taken over the Hidden Land and made the royal family his prisoners. When Reed, Johnny and Ben fight off the Alphas and fly to the Hidden Land themselves, they are attacked by Maximus' android creation Zorr and are easily defeated.
With nobody to oppose him, Maximus reveals his plan to use a giant hypno-gun to make the entire population of Earth his loyal slaves.