In Heidelberg, French army captain Henri Rochard seeks out WAC lieutenant Catherine Gates and, when he finds her, returns a collection of underwear.  Deeply embarrassed and angered, Cathy follows him and demands that he come back to her office and explain to her fellow WACs that their laundry was accidentally switched.  Henri refuses, and the two continue the quarreling that has characterized their relationship since their first mission together.

Henri informs Cathy that he is in Heidelberg to meet the WAC who will accompany him on his next mission, but soon learns that his prospective partner has been reassigned, and Cathy will again be working with him.  Next they discover that the only available transport is a motorcycle with a side car; because only Cathy has been cleared to operate the machine, Henri will have to ride in the sidecar.  After several mishaps, including a road block, a near plunge over a waterfall, and losing their way, Cathy and Henri arrive at their destination, Bad Nauheim.

At the hotel, Cathy complains of back pain, and Henri offers to give her a back rub.  After she falls asleep, Henri tries to leave her room, but discovers that the door handle has fallen off, trapping him inside.  Henri spends an uncomfortable night in a chair, and in the morning, Cathy refuses to believe his story.  Unknown to Henri, the innkeeper's wife has replaced the knob, and so, when he again tries the door, it opens easily.  Eventually, the innkeeper's wife explains everything to Cathy, but not before Henri falls off the roof while trying to keep his presence in Cathy's room a secret.

Later, Henri disguises himself to search for Schindler, a black market lens grinder.  He refuses to let Cathy help him, so she has breakfast with a fellow officer.  From him, she learns that the black market is about to be raided, and when Henri asks her to vouch for his identity, she follows his earlier orders not to reveal that she knows him, and allows the police to arrest him.  While Henri is in jail, Cathy finds Schindler, who happily agrees to leave Germany and ply his trade in France.

Later, she apologizes to a furious Henri, and by the time they return to Heidelberg, they have fallen in love.  After a great deal of red tape and interference by well-meaning friends, Cathy and Henri are married in three different ceremonies.  Before they can consummate the marriage, however, Cathy is ordered back to the United States.  They subsequently learn that the only way Henri can get a visa to emigrate with her is under the War Bride Act, as a spouse of a member of the expeditionary forces.  After many misunderstandings, Henri is granted permission to sail for America with Cathy, but before they leave, circumstances and Army regulations conspire to keep them from spending the night together.  Finally, in order to get past unbelieving Navy officers, Henri must dress as a woman.  The deception works, but once underway, Henri's disguise is penetrated, and he is arrested.  Cathy manages to straighten out the situation, and although he is free to leave the room where he has been imprisoned, Henri invites Cathy in.  After he locks the door on the inside and throws away the key, Henri and Cathy finally have their wedding night.

Notes
Henri Rochard, the pen name of Dr. Roger H. Charlier, first published his story, then entitled "Male War Bride Trial to Army," in the Baltimore Sun on September 28, 1947.  A condensed version of the story appeared in the Nov 1947 issue of Reader's Digest, retitled I Was a Male War Bride.  (A modern source records the title of Rochard's story as "I Was an Alien Spouse of Female Military Personnel Enroute to the United States Under Public Law 271 of the Congress.")  According to a November 12, 1947 LAT news item, Rex Harrison originally was to star in the film.

Some scenes in the film were shot in Germany.  Heidelberg, which had not been damaged during wartime bombing, was the major location; other scenes were filmed in bomb-shattered Manheim and Frankfurt and the old village of Zuzenhausen.  Twentieth-Century Fox publicity material reports that after three months of filming in Germany, the troupe moved to Shepperton Studios in London, England, where many of the actors became ill:  Ann Sheridan developed pneumonia from filming in bad weather and was bedridden for three weeks; Randy Stuart was stricken with jaundice; then Cary Grant became ill with infectious hepatitis and lost thirty-seven pounds; and Hawks broke out in hives. Production shut down on February 8, 1949, according to information in the Twentieth Century-Fox Records of the Legal Department, located at the UCLA Arts - Special Collections Library.  Filming resumed in early May 1949, after Grant regained the weight he lost during his illness.

A February 4, 1953 Var news item reported that author Charlier and his wife, the former Marie H. Glennon, were suing Twentieth Century-Fox for breaching their original 1947 deal by releasing a serial version of the screenplay to the German magazine Herz Dame . The outcome of the suit has not been determined.

Material included in studio records adds the following information about the production: Producer Sol C. Siegel suggested Louis Jourdan for the lead.  Studio publicity adds Buzz Barbee and William Janssen to the cast.  According to the studio legal files, Mary Helen Fay and Laszlo Bus-Fekete worked on early drafts of the script but did not contribute to the final screenplay.  According to studio records, actor William Challee was to appear in the film, but as he had not been filmed prior to Grant's illness, his contract was terminated.  After filming resumed in the U.S., some scenes were shot on location at the docks in Long Beach, California.  The following crew members received credit in British advertising only:  Art Director, C.P. Norman; Film Editor, Manuel Del Campo; Sd, Buster Ambler; Production Manager, Ronnie Kinnoch; Assistant Director, John Bremer; Camera Operator, Robert Walker.

Modern sources add the following information about the production: Cary Grant did his own stunts.  For the portion of the picture in which he dresses as a WAC, Grant wanted to play the character with effeminate gestures, but Hawks convinced him it would be funnier if he just acted like a man in women's clothes.  A Lux Radio Theater version of the film was to be broadcast on August 28, 1950, starring Grant and Sheridan, but was canceled when Charlier failed to release his radio rights in the story to Lux.