Tales of Suspense, Vol. 1

Somewhere Lurks the Phantom - Tony Stark figures out a way to upgrade his armor so he can finally take it off. He announces a fake engagement to allow Pepper to move on and be with Happy Hogan, and then has to deal with a saboteur known only as the Phantom.

The Origin of Captain America - During World War II, skinny, sickly Steve Rogers is selected as a possible recipient of Dr. Erskine's revolutionary formula to turn him into a peak human. It succeeds, but Erskine is killed and the formula cannot be reproduced. Rogers takes on the mantle of Captain America, and mentors young Bucky Barnes to become his partner in the fight for democracy.