Gunfighter's Moon is a story about Frank Morgan, a notorious and feared gunfighter who has lived his life on the run. His face and eyes reveal a man hardened by his past, but still holding onto passion.
Upon receiving a telegram from Linda, an old lover played by Kay Lenz, Frank abandons his current woman and rides to Linda without hesitation. However, upon arrival, he discovers that Linda is now happily married to the owner of the local general store.
The only reminder of their past is a daughter, who Frank is surprised to learn is his own. Linda has kept the truth hidden from their daughter, creating a fictional hero father who died at the First Battle of Bull Run.
Linda's reason for calling Frank is not romantic, but rather a plea for help. Her husband has been appointed temporary sheriff after a failed bank robbery resulted in deaths. With a prisoner's cousin set to be released and seeking revenge, Linda fears for her husband's life.
Frank must come to terms with the fact that Linda and their daughter are out of reach, and decide whether to help the man who now has the woman he loves or simply ride away.