|When printer John R. Hodges (Monty Woolley) is forced to retire at age 65 because of a company policy, he decides to do something about it. Dyeing his hair black, he poses as Harold P. Cleveland, the president of his former employer"s parent company and goes on an inspection tour of his old workplace, with the firm"s nervous, mystified executives in tow. While walking around the plant, Hodges runs into Joe Elliott (David Wayne), the boyfriend of his granddaughter Alice (Jean Peters), and winks at him to let him in on the joke. Afterward, Hodges complains about the lack of experienced older employees, causing company president Louis McKinley (Albert Dekker) to promise to rescind the retirement policy and rehire all those affected by it within the past year.
However, before he can depart, Hodges finds that McKinley has arranged for him to address the local Chamber of Commerce. Hodges is up to the challenge, delivering a rousing speech about the virtues of the older worker. He receive a standing ovation, the newspapers praise him, and even the stock market rises on the optimism generated.
Hodges is taken to dinner by McKinley and his neglected wife Lucille (Constance Bennett). McKinley, it turns out, is more interested in his curvaceous private secretary Harriet (Marilyn Monroe). Hodges has a wonderful time, dancing the night away with Lucille. Swept away by his compliments and attention, she fancies herself in love with him. Later that night, she tells her dumbfounded husband that she wants a divorce.
Meanwhile, Joe is unable to convince anybody that Cleveland is actually an impostor. Frank Erickson (Clinton Sundberg), his rival for a promotion, and the entire Hodges family - son George (Allyn Joslyn), daughter-in-law Della (Thelma Ritter), and Alice - all think Joe is crazy. However, when Hodges returns home with his dyed hair, Joe is vindicated. Since Hodges will be exposed anyway, Della proposes that Joe turn him in so that he can get the promotion, but Joe refuses to do it. The next day, Erickson finally believes Joe and tries to warn their mutual boss Horace Gallagher (Wally Brown), but Gallagher thinks Erickson is mentally unstable and gives the promotion to Joe. This enables Joe to finally propose to Alice.
Meanwhile, the real Harold Cleveland (Minor Watson) is in an awkward position. The speech has done wonders for his and his company"s image and even raised the price of the company"s stock, but he is unsure of his impostor"s motives. When McKinley discovers Hodges" identity and informs Cleveland, he decides to pay him a visit.
Lucille gets there first, but Hodges tells her he will not come between a man and his wife, and that he suspects she is still in love with her husband. McKinley barges in and apologizes to his wife; the happy couple kiss and make up.
When Cleveland meets Hodges, he is reassured that the old man has no sinister intentions. Cleveland is so impressed that he offers Hodges a job advising him on public relations, but gets turned down.
Monty Woolley as John R. Hodges
Thelma Ritter as Della Hodges
David Wayne as Joe Elliott
Jean Peters as Alice Hodges
Constance Bennett as Lucille McKinley
Marilyn Monroe as Harriet
Allyn Joslyn as George Hodges
Albert Dekker as Louis McKinley
Clinton Sundberg as Frank Erickson
Minor Watson as Harold P. Cleveland
Wally Brown as Horace Gallagher
Russ Tamblyn as Willie McKinley (as Rusty Tamblyn), the McKinleys" son