It proved to be a rather entertaining thriller, largely thanks to Edward Arnold’s impressive portrayal of "Jim McLain," a visually impaired detective. He’s enlisted by an old friend, "Norma" (Ann Harding), who needs his help in discouraging one of her stepdaughter's suitors. Following the murder of this suitor and suspicion falling on another associate, he arrives at her residence with his quick and helpful dog, "Friday," uncovering a complicated scheme involving Nazis attempting to acquire confidential documents belonging to her husband. The storyline does stretch credibility somewhat, but Arnold delivers an exceptional performance – particularly during the musical sequences – as does his very nimble dog. Mantan Moreland makes appearances in his familiar butler role, contributing some lighthearted moments, and generally it’s a respectable film from the wartime era.

Source on TMDB