Set in 1962 Hong Kong, the story follows Chow Mo-wan, a journalist, and Su Li-zhen, a secretary, who move into neighboring apartments on the same day. Both are married to spouses who are frequently away for work, leaving them to navigate their lonely lives in the cramped, bustling environment of their tenement building. As they spend more time together, they discover that their respective spouses are having an affair with each other. Bound by the shared betrayal, Chow and Su begin to spend time together, reenacting how the affair might have started and seeking solace in one another. As they grow closer, they struggle to maintain their moral integrity and resist the temptation to succumb to their own burgeoning feelings, fearing they will become no better than the people who betrayed them. The film is a poignant meditation on memory, unrequited love, and the passage of time.