Part of the Man Trilogy (along with A Serious Man and A Single Man), The Other Man is based on a short story by Bernhard Schlink (The Reader) and directed by Richard Eyre (Notes on a Scandal). In case anybody is still in the dark about the plot after watching the trailer, here it is in words of mostly one syllable:
The tale of a guy who thinks his wife is a cheat, and then sets out to track down the other man.
[Incidentally, The Other Man has been an immensely popular title in film history, as far back as 100 years ago, with no fewer than 6 movies entitled The Other Man between 1911 and 1918. There was a movie called The Other Man in 2006 and there’s another one due out next year. IMDb lists 28 movies entitled The Other Woman.]