The Apartmentis a 1960 American comedy-drama film produced and directed by Billy Wilder , and starring Jack Lemmon , Shirley MacLaine , and Fred MacMurray . It was Wilder's follow-up to the enormously popularSome Like It Hotand, like its predecessor, was a commercial and critical hit, grossing $25 million at the box office. The film was nominated for ten Academy Awards , and won five, including Best Picture .

It was later adapted as a Broadway musical,Promises, Promises, with a book by Neil Simon , music by Burt Bacharach and lyrics by Hal David .

C. C. Baxter ( Jack Lemmon ) is a lonely office drone for an insurance company in New York City . In order to climb the corporate ladder, Baxter allows four company managers to use his Upper West Side apartment for their various extramarital liaisons. Unhappy with the situation, but unwilling to challenge the managers, Baxter juggles their conflicting demands, while hoping to catch the eye of fetching elevator operator Fran Kubelik ( Shirley MacLaine ). Meanwhile Baxter's neighbors assume he is a "good time Charlie" who brings home a different drunken woman every night. Baxter accepts their criticism rather than reveal the truth.

The four managers write glowing reports about Baxter—so glowing that personnel director Mr. Sheldrake ( Fred MacMurray ) suspects something illicit behind the praise, and summons Baxter to his office in order to confront him. Sheldrake lets Baxter's promotion go unchallenged on the condition that he be allowed to use the apartment as well, starting that night. Sheldrake gives Baxter two tickets to the Broadway musicalThe Music Manto ensure his absence. Delighted about his promotion, Baxter asks Miss Kubelik to meet him at the theatre. She agrees; however (unbeknownst to Baxter), she is in reality Sheldrake's mistress. Though she intends to break off the affair that night, she is instead charmed by Sheldrake to Baxter's apartment. Baxter is disappointed at being stood up, but is willing to forgive Miss Kubelik.