Witness for the Prosecution

A classic Billy Wilder-helmed film with a lengthy English court trial at the end, replete with cross-examination galore. The ending has about a dozen plot twists in the last five minutes or so, but that doesn't detract from the rest of the film. Plus, Agatha Christie wrote it. I've only read one of her books ("And Then There Were None," also known as "Ten Little Indians"), but I thought it was great.