During a cross-country lecture tour through small-town Ohio, Sheridan Whiteside, Nathan Lane, injures his hip after slipping on the icy steps of the Stanleys' house, where he is due to dine as a publicity stunt. He opts to recuperate there over the Christmas holidays to avoid a looming lawsuit with his attorney. June Stanley, Mary Catherine Garrison, hosts him, and Whiteside’s stay begins to reshape the household routines in unexpected ways.
The overbearing celebrity soon dominates the household, commandeering the most prominent rooms and restricting Mr. Stanley, Terry Beaver, to the upper story, while Mrs. Ernest W. Stanley, Linda Stephens, is drawn into his orbit as well. He also draws the attention of the local doctor, William Duell as Dr. Bradley, coaxing him to exaggerate Whiteside’s recovery by promising to read the doctor’s unpublished magnum opus, which Whiteside promptly disregards. His reconnaissance of the household includes a flurry of calls to important figures—Winston Churchill and Ethiopian Emperor Haile Selassie—made from the comfort of the home, and he accepts extravagant gifts from naturalists, such as live penguins and an octopus, to entertain his guests and satisfy his whims.
Whiteside’s influence extends to social plans as he invites convicts from the state penitentiary, part of his reputation-building luncheon, to emphasize the reach of his celebrity. His nurse and aide, Maggie Cutler, Harriet Sansom Harris, becomes entangled in both his schemes and a budding romance with local newspaperman Bert Jefferson, Hank Stratton; when Bert reads his play to Maggie, she urges Whiteside to share it with his contacts. After a few dates, Maggie announces she will quit Whiteside’s employment to marry Bert, though Bert himself has not yet grasped the news.
Determined not to lose such an efficient helper, Whiteside begins to sabotage the burgeoning romance. He presses Lorraine Sheldon, Jean Smart, a glamorous actress, to accept a leading role in a supposed “upcoming” play, hoping she will steal Bert away from Maggie. Lorraine, sensing a chance for a big break, becomes entangled in the plot, and Maggie, realizing Whiteside’s meddling, joins with his friend Beverly Carlton, Byron Jennings, in a ruse to deter Lorraine by impersonating her wealthy patron, Lord Cedric Bottomley, and signaling a mocked future. When Lorraine uncovers the deception, she vows to keep Bert’s attention.
Undeterred, Whiteside and Banjo, Lewis J. Stadlen, devise a more spectacular plan to remove Lorraine from the picture. They appeal to Lorraine’s vanity, orchestrating a staged scenario that sees her trapped in an Egyptian sarcophagus and shipped off to Nova Scotia. The household’s tempers fray, and Mr. Stanley finally swears out a warrant ordering Whiteside to leave within 15 minutes.
Yet Whiteside has one last card to play. He reminds Mr. Stanley of Harriet’s past as an infamous axe murderer and uses the threat of exposure to coerce him into dropping the warrant and allowing the family’s children to chart their own futures. As Whiteside prepares to depart, a call from First Lady Eleanor Roosevelt interrupts the moment; Whiteside, distracted by the news, slips on the Stanleys’ icy steps again and is carried back inside, much to Mr. Stanley’s consternation, while Eleanor Roosevelt’s message is left unheard on the unattended line.
