As I write this review, there have been two reviews of this film posted here, each of which gave it five stars. I enjoyed the movie, but I have to say that five stars is a little over-exuberant for this particular movie. I would reserve that sort of rating for a Casablanca, The Lady Vanishes, Duck Soup, and quite a few others, but I don't think those who made this movie intended it to be an undying work of cinema art, and so I'm giving it three stars, recognizing it as a solid, workmanlike product churned out by the studio system in (as the special features on the DVD point out several times), just nineteen days of shooting.
Let me be a little more specific. I'm going to limit what I say to a certain extent, because this is a film based on a story by John Dickson Carr, the master of "locked room" mysteries, and a large part of the film's dramatic energy stems from the fact that the story starts out with one of those seemingly impossible situations -- the young, starry-eyed bride boards the ocean liner with her wonderful new husband, only to have him disappear within minutes after boarding, and to have no one else on board the ship acknowledge that he ever existed. (Similar in some ways to The Lady Vanishes, mentioned above as a five-star effort of this sort by Mr. Hitchcock.)
Anyway, I am honor-bound not to write any spoilers, and I won't. What I will say is that the film is very well made. The special features point out that this movie used sets left over from the "Titanic" film of that era, so the quality of the shipboard scenes is quite good from a technical point of view. The acting and direction are fine, and the movie is very short and to the point. There is a good air of mystery, and we, the viewers, are left wondering what on earth (sea, I should say) is going on until a "reveal" moment by a villain about halfway through. (I hope that wasn't a spoiler, but, yes, there is at least one villain; it wasn't all just a big mistake.)
My main criticism isn't really anything negative -- the movie is well done for what it is. What it is, in my opinion, is a good example of the films cranked out like sausages back in the days before television caught on. I'm a bit too young to remember, but I believe the movies changed at least once per week in those days, and there often were double features. This would not have been a bill-topper. It strikes me as a woman-oriented melodrama, with a plot and style bearing hallmarks of the mass-produced romance novel -- young woman in grave jeopardy on board a ship; no one is listening to her, except a tall, dark, and handsome doctor (Michael Rennie), who is attentive, suave, and warm. There is not much in the way of subtlety or complexity in the film. There is an effective build-up of suspense, and some fairly standard "shocks" from bumping into things or hearing strange noises, or doors creaking, but nothing that really resonates as having great artistic merit.
Also, although I'm not at liberty to discuss them with those of you who haven't yet seen the film, I saw what I believe to be fairly obvious holes in the plot. A story like this by definition has to be somewhat contrived, in order to set up the seemingly impossible situation, but, once the solution was revealed, I had to ask myself how that solution would have been possible, practically speaking. In other words, how could the villain(s) have pulled that off, realistically. The movie does not do a great job of explaining the solution in any detail.
But, I have no regrets at having bought and watched the DVD. The movie is very nicely transferred to DVD; both audio and video are fine, and the featurette on the making of the film, with Jeanne Crain's grand-daughter and others, was quite informative. The movie is a good, entertaining diversion for a rainy afternoon, but it rates no more than a solid three stars.