Battle at The Center of the Earth - Marvel Team Up #17 (1974)

Last issue, Captain Marvel (the dude, not Brie Larson) got sucked up into a crystal and disappeared . Unable to figure out what happened, Spidey reaches out to the smartest man on earth, Mister Fantastic! They figure out he's in the middle of the earth, the domain of the Mole Man. Can they free the hero before it's too late?