Running Scared (1972)

An undergraduate, "Casey" Case, commits suicide in his college rooms, watched by his best friend Tom, who respects his right to end his life and does nothing to stop him. Soon afterwards, Tom receives an angry letter from Casey's sister, Ellen, whom he has never met, enclosing a bullet with which, she sarcastically suggests, he too can kill himself. Sent down from university, Tom becomes intrigued by the Case family and, posing under a false name, makes their acquaintance. To his own surprise, he finds himself falling in love with Ellen; but does she know who he really is?