Milquetoast Robert Wilson and his meek wife Catherine have been married for four years when Robert prepares to join the British navy and fight in World War II. The day he leaves, he battles nerves and stomach problems while Cathy, suffering from one of her endless colds, quietly says goodbye. During boot camp, Robert struggles with seasickness and lowly conditions. A short time later, Cathy joins the Wrens, the Women's Naval Service, and has similar difficulties with the arduous training schedule. Soon, however, Cathy's tough friend, Dizzy Clayton, teaches her how to improve her appearance and have more confidence, while Robert becomes more rugged and confident himself. As London suffers continued bombing over the next few years, Robert and Cathy write to each other, but never manage to have leave at the same time. They both advance in their positions, learning much about themselves and their strengths as they succeed. Robert describes Cathy to his friends as dependable, while she tells Dizzy that Robert is not as exciting as Dizzy's dashing cousin, Richard, with whom she has been spending much of her free time. One day, Robert's boat is attacked by enemy fire, and although his hands are badly burned, he spends five days rowing his shipmates to safety. While recuperating in the hospital, he meets a nurse, Elena, and soon asks her to dinner. After they dance together, Elena, a war widow, kisses him and then leaves. Days later in England, as Richard declares his love for her, Cathy informs him that she must meet Robert for ten days, for the first time in three years. As Cathy and Robert travel separately toward London, each thinks about how little either one wants to return to their dreary former life. Robert arrives first at their flat with his friend, Scotty, complaining about having to see Cathy, but when she telephones from the street and declares that she no longer loves him, he is hurt. They meet on a street corner, which was dark because of the nightly blackouts and agree to a divorce, each sure that the other one will be helpless alone. When they enter a pub to continue the discussion, Cathy is pleasantly startled at Robert's strength and handsomeness, and Robert is shocked to see how confident and glamorous Cathy looks. As they talk, the pub proprietors, who are celebrating their fiftieth wedding anniversary, invite everyone to dance, and Cathy and Robert dance together for the first time. When Dizzy and Scotty join them, however, Scotty clumsily reveals to Cathy that Robert has described her as dependent. She storms out and they fight in the street, after which Robert wanders the streets in confusion, while Cathy visits the flat and reminisces about the love they used to share. Robert finds himself drawn back to her, and when he arrives, Cathy shows him how the walls that used to block their windows have come down in the bombing, flooding the apartment with light. They look out over the ravaged city and, realizing that anything can be built back up again, no matter how long it takes, they kiss.