Witness for the prosecution (1957)
Witness for the prosecution, an adaptation of a story of the same name by Agatha Christie is a brilliant courtroom drama film. Directed by Billy Wilder, the movie is as suspenseful as any of Hitchcock's classics. In fact it was so suspenseful that the credits at the end of the movie read "The management of this theatre suggests that for the greater entertainment of your friends who have not yet seen the picture, you will not divulge, to anyone, the secret of the ending of Witness for the Prosecution."
Acting too is brilliant, in fact elaborate in the movie. Marlene Dietrich in one of her last roles in movies shines in the limited screen time she has. Even Charles Laughton as a passionate barrister who takes up the case despite having just recovered from a heart attack, has some really witty lines.