2007. Starring Tony Leung, Wei Tang. Directed by Ang Lee.

The setting is Japan-occupied China in 1942. Wong Chia Chi (Wei Tang) is a young student pulled into an acting troup — and underground resistance cell — by a classmate. Her role in a patriotic play ignites a revolutionary fire in her, which may be fueled by an attraction to the group’s leader, Kuang Yu Min (Lee-Hom Wang), but forces her into the lead role when there’s an opportunity to get close to, and eventually assassinate, an official of the occupation government, Mr. Yee (Tony Leung).

Mr. Yee hasn’t achieved his position by trusting people, and getting close to him has proven dangerous. Wong instead befriends his wife (Joan Chen) and becomes familiar to him through the frequent mah-jongg games his Mrs. Yee hosts. Wong quickly arouses Mr. Yee’s interest — and suspicion. But he orchestrates a meeting to either seduce her or interrogate her, and brutally succeeds at both. Committed to the plan and the cause, she continues to meet him, pulled in deeper by the chance to get closer and the man she finds up close.

This is a film about vulnerability, the need to exploit it and the need to conceal it. You probably should be warned about the sex scenes — they are graphic and intense. But it is in those encounters where guards are let down and character roles abandoned, where identity comes close to the surface. Both are vulnerable during the trysts — Yee leaves his gun next to the bed, Wong is escorted to out-of-the-way apartments, never sure whether her real intentions have been uncovered.

Tony Leung is a well-known, well-respected actor (best known in the US for Wong Kar-wai’s In The Mood For Love), and Lee-Hom Wang is apparently a huge pop music star across Asia, but I don’t think they are the biggest stars here. Those credits belong to Wei Tang, and that beautiful face.

It’s very surprising to learn that this is Wei Tang’s first film. She combines the spy’s wariness and the actor’s poise in her onscreen dual role and, as tough as those love scenes must have been to shoot, she’s graceful and honest in them. And that face — the camera loves Wei Tang’s face the way the camera loved Ingrid Bergman’s — focused on her dark eyes, and a smile that appears and recedes at the corners of her mouth almost imperceptibly.

More than two-and-a-half hours long, in Chinese, with the aforementioned sex scenes and a clumsy (but realistic) murder, Lust, Caution is more of a commitment than a date movie. But Ang Lee has made another well-directed, well-acted story with a few intriguing twists. And Wei Tang as the focus of nearly every scene is worth the price of admission.