This is the kind of romantic supernatural fantasy which was popular just after WWII. It's set at the start of the twentieth century in England, Hollywood. Gene Tierney is a recent widow, and moves to a picturesque seaside town in order to find herself and escape her oppressive in-laws. There, Mrs. Muir meets the ghost of a sea captain (Rex Harrison) who narrates to her a best selling tale of the oceans.
Maybe in the years after the war, it was likely there would be an audience for a story about a bereaved woman who falls in love with a man who (probably) only exists in her thoughts. And about a widow who must find the strength to go on alone. There are many interesting themes on the subjects of loss, and also the creative process.
But mostly the film is a charming comedy-romance. Rex Harrison is engaging as the salty, barnacled sea-dog. The beautiful Tierney is extremely sympathetic as a woman searching for a second chance in life, which is sadly unfulfilled. When she seeks to re-engage with the world through George Sanders' decadent rake, she is badly let down.
Joe Mankiewicz creates a rich period atmosphere from his studio sets and the shadowy, expressionist photography. And there's a superb score from Bernard Herrmann. Sure, it's a sentimental tearjerker, but there is intelligence and craft too. The stars are wonderful together; they elevate the whole film and make you care, which makes the magical ending a real heartbreaker.