This is a better produced television sequel than the "origin" story. It begins with Captain America rescuing an old woman's pension check from some thugs. Then it goes to where he works at a government agency. Here, Dr. Wendy Day is portrayed by Connie Sellecca (GREATEST AMERICAN HERO), taking over for Heather Menzies.
He's sent to investigate a small town where weird things are happening, like farm animals dying of old age when they are only a few weeks old. He hits it up with a mother and her kid, who are reluctant to talk about what's really going on. It's when he stands up for them and defeats some of the local thugs that they loosen up. A hidden lab has developed a substance that increases aging. This is all the diabolical plan of a General named Miguel (Christopher Lee), who plans on exposing cities to this and then asking a high price for the antidote. It's all kind of convoluted. In the end Miguel gets the chemical spilled on himself and starts aging rapidly, like in a Dracula movie, which I guess is sort of an in-joke. Rebb and Chris Lee would appear together again, a few years later, in HOWLING II: YOUR SISTER IS A WEREWOLF (1985).