Tales to Astonish, Vol. 1

Henry Pym has figured out how to increase his size as well as reduce it, allowing him to take on the mantle of Giant Man. (He chooses not to share this advance with Janet, and doesn't explain why not.) He does this while the police hunt for the Living Eraser, who is able to erase people with the wave of his hand. He erases our heroes, sending them into a parallel dimension, where they are to be forced to help develop atomic weapons. Hank and Janet use their size changing capsules to rescue the others and return everyone home.