 The original music score is by Bill Conti and the song "Unfaithfully Yours (One Love)" was written for the film and performed by Stephen Bishop.Claude Eastman (Dudley Moore) is a composer and the conductor of a prestigious symphony who has recently married beautiful Daniella (Nastassja Kinski), a much younger woman.While travelling, he sends a message to his friend Norman Robbins (Albert Brooks) to keep an eye on his wife, but the message is garbled by Claude's Italian valet Giuseppe (Richard Libertini), and instead of looking after Daniella, Norman hires a private detective named Keller (Richard B. Shull) to investigate her.