In the turmoil of World War I, Myra Deauville, an American showgirl, finds herself struggling in London in 1917, desperately seeking a way to return home. With her financial resources depleted, she reluctantly turns to soliciting on Waterloo Bridge, a well-known spot for soldiers on leave. It is during this difficult time that she crosses paths with Roy Cronin, a sensitive Canadian soldier recuperating from his injuries sustained in France. Captivated by Roy’s innocence and vulnerability, Myra chooses not to engage in her usual business transaction and instead offers him a simple invitation to join her for tea at her apartment.
The next day, as Myra prepares to part ways with Roy, her neighbor Kitty, who also works in the same trade, spots him lingering outside their boarding house. Oblivious to the fact that their landlady, Mrs. Hobley, has been compelled to run a brothel due to her husband’s imprisonment, Kitty seizes the moment to persuade Myra to consider Roy's proposal as a means of survival. Kitty argues that providing comfort to a lonely soldier could bring some solace in a chaotic world, framing it as a moral choice in light of Myra's difficult circumstances.
Meanwhile, Mrs. Hobley overhears the discussions about Myra's interactions with Roy and, focused on her own self-interest, urges Myra to accept his offer. She believes that this arrangement could not only alleviate Myra's financial struggles but also ensure the smooth running of her boarding house. Eventually, Roy proposes to Myra, and despite her initial reservations, she yields to the pressure. However, overwhelmed with guilt regarding the situation, Myra ultimately decides to slip away before the arrangement can be fulfilled.
As the war continues, Roy allocates part of his military pay to support Myra and even names her as the beneficiary of his life insurance. Despite the grim realities of their circumstances, Mrs. Hobley reveals to Roy the truth of Myra’s line of work, yet he accepts the harsh truths of wartime life without faltering. When he returns to Camp Bramshott, he encounters Myra again at Waterloo Bridge, this time insisting that she accept his financial support and sign the necessary paperwork for the life insurance policy.
With an ominous feeling looming over her, Myra agrees, only to find herself caught in the devastation of a sudden German air raid that strikes the city. Amidst the chaos that engulfs her, her cigarette extinguishes as the bombs begin to fall, leaving her fate uncertain in this tragic love story set against the backdrop of war.
