"The Return of the Mole Man!" 22 pages.
Reed suspects that Sue has unlocked abilities, and helps her discover her ability to create an invisible shield and to make other objects invisible.
A wave of neighborhood complaints force the Fantastic Four to move their HQ to a deserted island, but they find the island has an occupant, the Mole Man, who plans on instigating World War III by stealing a major city from both the the USSR and the USA.
The FF thwart his plans, and send him running for his life when Reed changes the circuits on the Mole Man's machine, sending the island to the bottom of the ocean.
Reprinted in Marvel Collectors' Item Classics #16.