Mary Peppertree (Deanna Durbin) starts a new job as a telephone operator at the White House, where her father Timothy has been working as a guard for many years. A former Supreme Court telephone operator, Mary takes her first call from David Paxton (Don Taylor), a fishing expert who insists on speaking to the President about a political issue involving a small Pacific island. After hanging up on him twice, Mary spends the rest of her day fielding calls from various Supreme Court justices who attempt to reconcile her with her former fiancé, Phillip Manning (Jeffrey Lynn), a Justice Department attorney.
Later that night, Mary meets Justice Peabody (Harry Davenport) at a restaurant to discuss her breakup with Phillip, who is also there. After resisting their efforts to reunite her with Phillip, Mary tells Phillip that she broke their engagement not because she saw him with another woman, but because she was not jealous about it. Their conversation about her hard day at the White House fending off calls from the "fish peddler" is overheard by David, who assures Mary that he will speak to the President, despite her interference.
The next morning at the White House gate, David attempts to bribe Mary with flowers and candy, only to have them thrown back into his face. Later, at the switchboard, Mary receives a call from the President. When Mary hiccups into the phone, the President sends his executive secretary, Harvey Elwood (Ray Collins), to check on her condition and offers her a paper bag to breathe into. When Phillip calls expecting to drive her to Justice Peabody's party that night, she declines, not wanting to resume their relationship. Later, as she is leaving work, Mary must drive David off the White House grounds to prevent his arrest. Mary asks David to escort her to the party, offering to introduce him to the President's secretary in exchange for the favor.
Meanwhile, the President, having overheard Mary telling Phillip that she would rather stay home than attend the party with him, sends Lt. Tom Farrington (Edmond O'Brien), a naval aide at the White House, to escort Mary. At the party, they cause a stir and not a little jealousy in Phillip. After a pleasant evening of singing around the piano, Tom escorts Mary home, where she notices they're being watched. After she kisses Tom goodnight and he leaves, she is confronted by David, who's been waiting on the porch all night. David kisses a startled Mary, who starts to hiccup again.
The next day, when the President learns that Mary was upset about not keeping her date with David, he calls the fishing expert himself to express his regrets. Later over lunch, Mary tells David she will arrange a meeting for him with Phillip who can help him with his political issue. That afternoon at the Peppertree home, Tom arrives with presidential orders to take Mary to a White House movie screening. When Phillip learns that Mary is with Tom, he questions David about his relationship with Mary. The frustrated marine biologist announces he is leaving town and that everyone in Washington seems to have a "Mary Peppertree fixation."
Meanwhile, Tom's friend, newspaper publisher Samuel Litchfield (Frank Conroy), complains to Elwood about Tom's involvement with Mary, a mere switchboard operator. When Mary and Tom arrive together at the restaurant, the owner, Gustav Heindel (Hugo Haas), tells Elwood he saw Mary kissing David. Elwood decides to handle the matter with the Navy personally. Phillip offers to put the Justice Department on the case and promises to clear up the matter in two days. That night, at Elwood's request, David takes Mary out on a date in Tom's place. After kissing David, Mary breaks out in hiccups, a sign that she is in love. When Phillip and Tom show up, a jealous David leaves in anger, believing she is also seeing them.
The next morning, Mary receives calls from Gustav and the Supreme Court justices congratulating her on her engagement to Phillip, and a call from the President congratulating her on her engagement to Tom! When Elwood learns that David is not technically a citizen of the United States, he has the young man arrested for illegally entering the country. Elwood soon discovers, however, that the Pacific island on which David was born and holds a deed is home to a strategic military base. If David is declared an alien, the Navy could be forced to move. Later that day, everyone arrives at Gustav's restaurant to try to resolve the issue. After meeting with the President's advisors, David fashions a Senate resolution for the American annexation of his island if Phillip and Tom are given appointments far from Washington, and he and Gustav are made United States citizens. The government readily agrees, and when Mary calls the President with the good news, David interrupts her conversation with a kiss, causing both of them to hiccup.Deanna Durbin as Mary Peppertree
Edmond O'Brien as Lt. Tom Farrington
Don Taylor as David Paxton
Jeffrey Lynn as Phillip Manning
Ray Collins as Harvey Elwood
Hugo Haas as Gustav Heindel
Harry Davenport as Justice Peabody
Griff Barnett as Timothy Peppertree
Katharine Alexander as Miss Harkness
James Todd as Justice Van Sloan
Morris Ankrum as Adm. Walton
Frank Conroy as Samuel Litchfield
Leon Belasco as Igor
Louise Beavers as Bertha
Raymond Greenleaf as Justice Williams
Charles Meredith as Justice Hastings
Adele Rowland as Mrs. Peabody
Mary Adams as Marge
Adrienne Marden as Hilda
Beatrice Roberts as Dorothy
Harry Cheshire as Col. Hedley
Donald Randolph as Asst. Attorney General
William Gould as Sen. Benning
The working titles of this film were White House Girl and Washington Girl. The music was written by Frank Skinner. The songs were conducted by Edgar Fairchild and staged by Nick Castle.
In his review for Allmovie, Craig Butler called it "a moderately entertaining mini-musical simply because of the charming presence of Deanna Durbin." Butler saw the film as an unsuccessful attempt at creating a romantic screwball comedy of the classic type, lacking the necessary keen eye on detail, organization, character, and wit. According to Butler, the screenplay lacks all of these. The main "gimmick", of the President of the United States getting personally involved in straightening out the love life of a switchboard operator, is "obnoxiously cute and simply too unbelievable." Butler does applaud de Cordova's direction and the acting—Harry Davenport is especially good as a Supreme Court justice—but it is not enough to salvage a poor script and unbelievable story. Butler concludes:
But it's Durbin who has to carry the movie, and she does a wonderful job, skipping through the messes of the plot without a care for how silly the whole thing is. And, of course, she sounds wonderful when she sings as well. Pretty much by herself, she makes Mary something really pretty merry.
In his 1948 review for The New York Times, Bosley Crowther called the film "a sly piece of propaganda against the administrators of our government in Washington." Crowther explained:
For no one could possibly have cooked up such a horribly-quaint and coy romance in which not only the President of the United States but four Supreme Court Justices play cupid to a telephone girl without deliberately intending to make those gentlemen appear terrific dopes.
According to Crowther, the filmmakers, whom he called "propagandists", manipulate the viewer into drawing negative conclusions about Washington and its leaders. The film also fails on an entertainment level, with "painful attempts at humor" and "flat jokes" about the "woefully lax and quixotic operations of White House officialdom."