John Ritter plays an unsuccessful actor who takes a job posing as comic-book hero Captain Avenger at comics stores and conventions. While thus garbed, Ritter foils a grocery store robbery. He skedaddles from the scene when the cops show up, leading witnesses to assume that he is a genuine costumed superhero, the sort that shows up to foil the villains and then modestly retreats after his job is done. Ritter is hired by the mayor's staff, who hope that the Captain Avenger tie-in will help the mayor win an upcoming election. This plan comes acropper, and Captain Avenger finds himself on the outs with the public. Prodded by his girlfriend Anne Archer to be himself and not rely on a costume and mask to gain adulation, Ritter becomes a bonafide hero when he rescues several citizens from a fire. Thanks to the enthusiastic performance of John Ritter, Hero at Large remains amusing even when you know what's going to happen next (a common occurrence in this film).
~ Hal Erickson, All Movie Guide