Mary Peppertree begins a new chapter as a telephone switchboard operator at the White House, following in the footsteps of her father, Timothy Peppertree, who has spent years guarding the premises. Her first day kicks off with a curious call from David Paxton, an ardent ichthyologist who insists on speaking to the President about a political issue involving a tiny Pacific island. After Mary hangs up on him twice, the day unfolds with a flood of calls from Supreme Court justices who try to coax her into reuniting with her former fiancé, Phillip Manning, a seasoned Justice Department attorney.
That evening, a chance encounter at a restaurant brings together the tangled threads of Mary’s day. She meets Justice Peabody to discuss her breakup with Phillip, a decision she explains was driven not by jealousy but by a sense that she wasn’t jealous enough to hold on. Their conversation about the day’s chaos is overheard by David Paxton, who offers to take the matter to the President himself, then storms off with a mix of determination and frustration.
The next morning at the White House gate, David tries to smooth things over with flowers and candy, only to have them rejected. Back at the switchboard, Mary then gets a call from the President himself. When she hiccups into the phone, the President sends his executive secretary, Harvey Elwood, to check on her condition and even offers a paper bag to help her breathe.
Phillip calls, hoping to secure a ride to a party hosted by Justice Peabody, but Mary declines, wary of resuming their relationship. Later, as she leaves work, Mary must escort David off the White House grounds to keep him from getting into further trouble. To balance the situation, she agrees to let David accompany her to the party if he can be introduced to the President’s secretary.
Meanwhile, the President, who overheard Mary telling Phillip she’d rather stay home, steps in with a plan of his own. He assigns Lt. Tom Farrington to accompany Mary to the upcoming event, a move that stirs a little jealousy in Phillip. At the party, a lively evening of singing around the piano unfolds, and after the festivities, Tom escorts Mary home. Her father watches from an upstairs window as Mary shares a moment with Tom and then, on leaving, is confronted by David waiting on the porch. A kiss from David sends Mary into another fit of hiccups.
The following day brings a mix of official concern and personal intrigue. The President reconsiders the political implications of Mary’s connections, calling the fish expert to express regret, but ultimately dismissing David’s fixation as a potential complication. Over lunch, Mary proposes arranging a meeting for David with Phillip to help him push his island-related agenda, signaling a new, more formal channel for his political issue.
That afternoon at the Peppertree home, Tom arrives with presidential orders to take Mary to a White House movie screening, a plan that puts Phillip in a tense position after he learns Mary is riding with Tom. Phillip confronts David about the situation, and the younger man nonchalantly announces he’s leaving town, remarking that Washington seems to be obsessed with Mary.
Back in the public eye, Tom’s circle grows tense. Samuel Litchfield, a newspaper publisher and Tom’s friend, voices his concerns to Elwood about Tom’s involvement with Mary. When Mary and Tom reach Gustav Heindel’s restaurant, the owner himself notes that he saw Mary kissing David, and Elwood decides to take up the issue at once with the Navy to manage a possible scandal.
Phillip proposes involving the Justice Department to resolve the situation within a couple of days, spurring a deeper dive into how far the personnel around the White House will go to safeguard Mary’s reputation and happiness. That night, at Elwood’s urging, David agrees to a date arranged in Tom’s stead, and back home on the porch, Mary’s kiss with David is followed by another episode of hiccups as the trio—Mary, Phillip, and Tom—arrive at a crossroads and accuse one another of being pawns in a larger game.
The next morning brings a wave of surprising congratulations: Gustav and several Supreme Court justices congratulate Mary on her engagement to Phillip, while the President himself calls with congratulations on her engagement to Tom. Elwood uncovers a critical twist: David is not a citizen, and his birth island houses a potential $300 million U.S. Naval base. If David were branded an alien, the Navy’s plans could shift, complicating the island’s status. A gathering at Gustav’s restaurant brings all factions together to resolve the issue, where a proposed Senate resolution would annex the island and grant citizenship to David and Gustav if Phillip and Tom receive distant appointments.
With the government’s consent in hand, Mary phones the President to share the good news. But in a final twist, David interrupts the call with a kiss, triggering the same hiccups that have punctuated their tangled relationship throughout the story. The film closes on a note that blends romance with a political wit, leaving the characters negotiating power, loyalty, and love in a landscape where personal desires intersect with national interests.
