As the story unfolds, Sheridan Whiteside, portrayed by Bette Davis, an infamous New York radio personality, experiences an unexpected mishap during his lecture tour, resulting in an unceremonious tumble down the icy steps of the Stanley family home in a quaint Ohio town. This prominent family, already fraught with anxiety over a looming $150,000 lawsuit with the esteemed lawyer Thomas E. Dewey, begrudgingly agrees to host Whiteside for the Christmas holidays, despite the disruption he promises to bring.
Upon settling in, Whiteside swiftly claims dominance over the Stanleys' household, commandeering the best rooms and relegating his hosts to the upper floors. In a scheming twist, he convinces Dr. Thompson to prolong his recovery time by fishing for a promise that he would read the doctor's unpublished work, only to utterly disregard it. Meanwhile, his extravagant lifestyle leads to sky-high phone bills as he entertains notable figures like Winston Churchill and Emperor Haile Selassie with grand tales of his own supposed greatness. The Stanleys' home becomes a veritable circus of chaos, with an influx of outlandish gifts from various naturalists, including live deliveries of four penguins and even an octopus.
Whiteside's magnetic presence inadvertently stirs creativity in the young couple, Richard and June, the Stanley children, who aspire to follow their artistic dreams, much to their father's chagrin. He whimsically characterizes Ernest Stanley’s peculiar sister Harriet as "straight out of the Hound of the Baskervilles," struggling to recollect where he has seen such a face before.
While the whirlwind of Whiteside's antics transpires, his devoted assistant Maggie Cutler, played by Ann Sheridan, finds herself developing feelings for local journalist Bert Jefferson. Following their shared moments, Bert's play captivates Maggie, leading her to ask Whiteside to facilitate its introduction to influential circles. As their relationship blossoms, Maggie surprises even herself with her intentions to marry Bert and leave her job, unaware that Bert is blissfully oblivious to her plans. In a flirtatious exchange, Bert gifts her a gold charm bracelet for Christmas, encapsulating their sweet early romance.
However, as the prospect of losing Maggie looms over Whiteside, he resorts to undesirable tactics to prevent this budding romance. He intentionally exaggerates his injuries, thus extending his stay in the Stanley home while devising schemes to disrupt Bert and Maggie’s relationship. Enter Lorraine Sheldon, a woman of undeniable charm, whom Whiteside seduces into a scheme aimed at stealing Bert’s affection by tantalizing her with a potential spotlight in an upcoming production by an alleged prominent playwright.
As Whitides’ influence grows, Maggie becomes increasingly anxious with Lorraine’s interference. In a clever counter-move, she teams up with Whiteside’s friend, Beverly Carlton, a master mimic and trickster, to impersonate the elusive Lord Cedric Bottomley, enticing Lorraine back to Palm Beach under false pretenses. When Lorraine realizes the ruse, she is outraged and vows revenge, determined to take Bert away from Maggie.
When Maggie uncovers Whiteside’s role in the scheme against Lorraine, she severs her ties with him, leaving him somewhat remorseful. In a final effort to eliminate Lorraine as a rival, Whiteside hatches a cunning plot alongside his friend Banjo. They appeal to Lorraine's vanity, tricking her into stepping into an ancient Egyptian sarcophagus, which they then seal and ship off to Nova Scotia.
The tension reaches a breaking point when Mr. Stanley submits to his frustrations, issuing a warrant for Whiteside to vacate his home within a tight timeframe of just 15 minutes. As the clock ticks down, Whiteside employs his cunning to blackmail Mr. Stanley into rescinding the warrant, threatening to expose Harriet's notorious past as an axe murderess—a juicy tidbit that gives him the upper hand.
As Whiteside prepares to exit, an unexpected phone call from First Lady Eleanor Roosevelt goes unanswered in the madness. In a final moment of comic chaos, Whiteside trips once more on the icy steps, only to be carried back inside by his loyal assistants, leaving Mr. Stanley exasperated and Eleanor’s call forgotten, muted by the hustle and bustle of the day’s misadventures.
