It's a shame to see such a promising beginning lead to something so underwhelming. Adapted from Agatha Christie’s well-regarded novel, initially titled Ten Little Indians, this “thriller” falls far short of expectations. Featuring an impressive lineup of performers like Barry Fitzgerald, Walter Houston, Louis Hayward, and Roland Young, and helmed by Rene Clair, one might reasonably expect a classic mystery thriller from the 1940s. The source material is certainly worthy: Christie’s novel is a truly excellent read—a gripping, occasionally terrifying exploration of human depravity and brutality, detailing shocking crimes orchestrated by someone deeply disturbed. It's a story I suggest to anyone who can stomach it; it ranks among the greatest ever told concerning corruption and terrible acts. The unfortunate truth is that the film proves to be a disheartening letdown. I later discovered this version was based on a stage play Christie herself wrote in 1943, six years after the novel’s release. Apparently, she altered the ending, seemingly concerned that the original conclusion would be too upsetting for audiences during wartime—a change that renders the film's title inaccurate! Rather than the novel's grim and violent finale, a sentimental romance was substituted. Miss Christie, why did you do that? Had they simply used the novel as their guide, the movie might have been decent. However, its production coincided with wartime conditions, which is why they opted for an altered ending instead. The film never manages to capture the unsettling atmosphere and suspense that are built into the book. The one thing I can say in its favor is that the acting is adequate; Walter Huston’s performance was particularly memorable. Honestly, you'll have a much better experience reading the actual And Then There Were None. In this film version, there were simply too many unresolved issues.

Source on TMDB