Iron Man, Vol. 1 #79 (1975)

Midnite On Murder Mountain!
In another fill in issue, Iron Man sees a young couple stranded in a rainstorm by a downed tree. Bringing them to the closest town under the guise of Tony Stark, the three check into a hotel to wait out the storm. Tony is awakened in the middle of the night by a scream, only to find that he has been locked in his room. Changing to Iron Man, and not wanting people to know Iron Man was in his room by breaking down the door from the inside, he instead decides to break out through the metal-shielded window from the inside. He follows the sound of screaming to the basement, where he meets Dr. Kurakill and her assistant, Quasar the Future Man. Kurakill has been devolving humans, and giving their power to the ape she evolved into Quasar. With the help of the young couple's cat (who may, in fact, be a devolved human victim of Dr. Kurakill herself) Iron Man breaks free, knocks Quasar unconscious, and shuts down Kurakill's equipment. Kurakill unleashes her army of devolved human apes, hoping they will overwhelm Iron Man, only to be attacked by them herself. Iron Man swears to devote the full resources at his disposal to the curing of the devolved humans, and the moral education of Quasar.
Release Date: 1975