Starring: Tony Leung, Tang Wei, Wang Lee-Horn, Joan Chen. Rated NC-17.

Despite the already notorious sex scenes that have earned it the MPAA’s dreaded NC-17 rating, Ang Lee’s Lust, Caution is a throwback to the cinema of the ’40s, an epic romance set against the backdrop of the Second World War. It has been criticized by some for being too cautious, for surrounding moments of graphic intimacy with arid melodrama, but that’s missing the point. The raging, conflicted passion that exists between Mr. Yee (Tony Leung) and Wang Chia Chi (Tang Wei) is constantly simmering beneath the surface of their calculated small talk; when it boils over, it is a jarring and often violent spectacle.

At first, their relationship seems little more than a dangerous charade. Yee is a high-ranking Chinese official in Shanghai, hunting down those who dare to resist the city’s Japanese occupiers. Wang is a naïve student whose crush on the boyishly handsome Kuang (Wang Lee-Hom) inspires her to join his ragtag crew of resistance fighters. Soon, she is working as a spy, infiltrating Yee’s home (and bedroom) in hopes of facilitating his assassination.

An unlikely romance blooms between them, despite Yee’s capacity for unspeakable cruelty and his appetite for rough sex. In his arms, Wang finds security and, eventually, tenderness. Despite her fierce patriotism, she ceases to view him as a treacherous tyrant and instead accepts him as a lover; he, in turn, risks his safety to be with her, sneaking away from his prim wife (Joan Chen, of Twin Peaks) and his barbaric comrades at every opportunity.

It is a strained romance, to be sure, rooted in deception and perilously volatile, but the raw intensity of the passion that consumes Wang and Yee is what makes Lust, Caution such a pleasure. Leung, a superstar in his native Hong Kong, brings to his role the watchful gravity of a man who feels alone in the world, forced to be on guard at all times lest he fall into the hands of the enemy. Tang, in her debut, is a revelation, making the transition from innocent schoolgirl to femme fatale in utterly convincing fashion. Together, they breathe vigorous life into a tale of star-crossed lovers whose longing for each other prompts them to throw caution to the wind.