Deathtrap (1982)

When once-successful playwright Sidney Bruhl (Michael Caine) sees his latest Broadway effort bomb on its opening night, he tumbles into despair -- until he receives a package from his former student Clifford Anderson (Christopher Reeve). Inside is an unproduced script that's better than anything Sidney has written in years. At the urging of his wife, Myra (Dyan Cannon), Sidney undertakes a plan to lure Clifford to his country home, murder him and then announce the script as his own work.