Purple Butterfly opens with a burst of train-engine steam on a cloudy morning, establishing what the movie is largely about: trains and rain. Purple Butterfly takes place in Manchuria in the late '20s and early '30s, at a time when the Japanese empire advanced into China, souring relations between the countries. Zhang Ziyi plays a young woman who gives up her Japanese lover (Tôru Nakamura) after a pro-Japan zealot murders her activist brother. Zhang joins a clandestine resistance organization, The Purple Butterfly, and when she meets Nakamura again years later, they're sworn enemies whose continuing attraction to each other may be part of a larger military strategy. The movie jumps back and forth in time, bridging the transitions with the sound of heavy rain and whistling trains. One memory couples with the next, as the story moves inexorably to its destination.
That opening burst of steam also represents the storytelling strategy of writer-director Lou Ye. Purple Butterfly is a hazy movie—not visually, but narratively. Like Lou's previous film, Suzhou River, Purple Butterfly deals with varying degrees of romantic obsession, and also like Suzhou River, it relies on a cryptology that only Lou can fully decode. In one key early scene, Liu Ye—a lovelorn would-be assassin whose suicidal behavior will drive the plot—gets off a train amid a hail of bullets, though who Liu is and why he's being shot at won't become clear until later, and maybe not even until a second viewing. The film should come with a libretto.
In spite of all that, Purple Butterfly is a sumptuously moody memory play. Like Wong Kar-wai and his obsessive romanticizing of early-'60s Hong Kong, Lou makes a crucial period of Chinese history into a stingingly personal portrait of regret, as his characters try to keep their relationships intact while civilization as they know it dissolves into a puddle. From Hiroshima Mon Amour to The English Patient, there's a noble cinematic tradition of love stories that double as metaphors for nations at war, and that seems to be partly what Purple Butterfly is showing: two countries struggling to love each other when they can't trust each other. But mostly, the movie's about heartbroken people gazing sadly through rain-streaked windows, waiting on the 5:15.