Lust, Caution ***1/2

In some ways, Ang Lee's Brokeback Mountain, adapted from a short story by Annie Proulx, and Ang Lee's Lust, Caution, adapted from a short story by Eileen Chang, aren't so very different.

Both, at the core, are about secret passion: two cowpokes who can't reveal their love for fear of the shame it'll bring on, or worse, and two Chinese in World War II Shanghai who can't reveal their love, for more complicated but no less dangerous reasons.

He - Yee (Hong Kong star Tony Leung) - is in the secret police, a collaborator with the occupying Japanese, a married man. She - Mrs. Mak (Tang Wei) - is likewise wed, or so she says. In fact, she is a young woman, only a few years out of university, who has banded with a group of theater students-turned-resistance fighters. Her mission, should she choose to accept: Seduce Yee, lure him from his security detail, and have him killed.

A rich, beautifully detailed espionage thriller that captures the bygone days of Shanghai - and 1940s Hollywood noirs' romantic evocations of same - Lust, Caution is also one of those rare movie experiences: Its scenes of the trysts between Yee and Mak, from their rough-stuff first encounter to the long, tangled love-making sessions of subsequent meetings, are truly erotic. With an unblinking camera and bold performances by Leung and Tang, these scenes - which make up maybe a dozen minutes of Lee's 2 hour, 37 minute drama - are not only what the film pivots on. They are what the conflicted souls played so exquisitely by Leung and Tang turn upon as well. (The scenes garnered the picture a rare NC-17 rating.)

Lust, Caution, adapted for the screen by longtime Lee associates James Schamus and Wang Hui Ling, is a story about transformation - by ideology and politics, by sex and love. As good as Leung is, the film belongs to Tang, a mainland Chinese actress whose character, Wong Chia Chi, is an innocent college kid, left behind by a father packed off to England. Her first transformation comes thanks to the theatrical troupe that invites her to join. Standing onstage, in a fiercely pro-China production, she quakes with feeling and speaks with force. The crowd goes nuts for her.

Later, Lee turns a couple of lovely scenes with Wong losing it at the movies, weepily watching Ingrid Bergman in Intermezzo, paying for a ticket for Penny Serenade.

Also very good in Lust, Caution is Kuang Yu Min (the Asian pop star Wang Leehom), as the leader of the theater company and of the resistance cell - a man clearly troubled by the lengths he's asked Wong to go to insinuate herself into Yee's world. And troubled by his own feelings of jealousy and desire.

Joan Chen, in a quiet, tamped-down role, plays Yee's wife, passing her days shopping, gossiping and playing endless hours of mahjong with her girlfriends - one of whom is the spy who calls herself Mrs. Mak.

Suspenseful and sexy, with sets, costumes and cars that recall another place and time, Lust, Caution nonetheless has something very modern - or timeless, really - going on: the urgent, all-consuming desire of one human for another.

Directed by Ang Lee. With Tony Leung, Tang Wei, Joan Chen and Wang Leehom. Distributed by Focus Features. In Mandarin with subtitles.

Running time: 2 hours, 37 mins.

Parent's guide: NC-17 (sex, nudity, violence, adult themes)

Playing at: Ritz at the Bourse, Showcase at the Ritz Center/NJEndText