Captain Duncan “Mac” Maclain is a formidable private detective who happens to be blind; but his other senses are sharper than average. He copes with his sight deficiency by being accompanied by a dog named Friday and a human assistant named Marty.
Mac is asked by his friend Norma to break up a romantic relationship between her seventeen-year-old step-daughter Barbara and a fifty-year-old actor. Mac finds the lover has been murdered and detects his body has been removed from the scene of the crime. The murder leads him to an Axis spy ring.