Sixteen years after Help!!!, Johnnie To is back within the confines of a hospital, this time to tell the story of a brain surgeon (Zhao Wei) who is reeling with guilt after committing two medical mistakes that cost one patient his mobility and another his consciousness. And things are not getting better, as a cop (Louis Koo) and his squad barge into her medical unit with a wounded criminal (Wallace Chung). There’s a bullet in his head but he’s still conscious and full of calculated sardonic playfulness. It soon appears that he was shot in the head while unarmed, during a violent interrogation where he was threatened and roughed up, until one the cops’ gun went off by accident. Thus the cop is walking on eggshells as he needs to both cover his squad and get information from the criminal in order to stop his accomplices, who are still on a robbery spree in Hong Kong. This puts him at odds with the brain surgeon, who is not ready to lose another patient, whether he be a ruthless gangster or not.

For much of its runtime, Johnnie To’s Three is a delightfully controlled, playful and clever little exercise in atmosphere and building tension. Never allowing himself one step outside of the hospital, the director fills us in on backstory through curt phone calls, quickly-glanced TV news report, and a lot of expressive stares. He surrounds the three leads with a gallery of buffoons (chief among which a hilarious Lo Hoi Pang as a childish old patient and Timmy Hung as computer-obsessed egoist), whips out a delicious three-minute tracking shot, and gives the audience a familiar landmark by having the great Lam Suet plays a well-meaning fat cop who loses important things and gets scolded by his boss. The hospital’s assorted corridors, antechambers, and operating rooms provide him with countless opportunities to play with depth of field, and the constant opening and closing of the curtains that separate beds is a sly nod to the film’s inherently theatrical construction: unity of action, time and place.

But Three isn’t simply a familiar exercise in style: there is discreet novelty to be found here. Examining the moral boundaries of cops desperate for justice and/or results is nothing new in Hong Kong cinema, but to put this back-to-back with a doctor’s struggle with her ethical duty (should a doctor save a criminal’s life if his survival means more innocent people will get hurt?) is a more uncommon set-up that here yields interesting though underdeveloped results. In clocking his film at a sharp 85 minutes, Johnnie To stops the unity of place from becoming stifling, but he also limits the aforementioned joint exploration of the beleaguered ethics of cops and doctors to the sketching stage. Luckily, he gets two terrific performances from Zhao Wei and Louis Koo. Zhao is both powerfully sympathetic, wearily human and utterly believable, anchoring the film with subtlety, while Koo brilliantly expresses his character’s ambivalence as a cop seeking justice but ever so close to losing sight of it to save his own ass. A sardonic edge constantly fights a stony righteousness and a creeping panic in his eyes, and while he and Zhao have a few tense face-offs, their chemistry is never fully utilized.

Sandwiched in between the two stars, Wallace Chung has a lot of fun as a modern, sometimes mildly cartoonish Loki-like villain, all knowing smirks and deceitful antics. In a way, it’s this more cartoonish side of the film that takes the lead in the final reel, as Michael Tse appears, a veritable terminator here to rescue the bed-ridden criminal. The build-up to the final shootout is a superbly choreographed ballet in the hospital’s corridors, but then as the guns start singing Johnnie To strangely drops the ball by resorting to unseemly amounts of awkward slow-motion and CGI blood, not to mention patchy green-screen work. Subtlety and believability are thrown out the window and the playfulness becomes a bit forced, even as irresistible sight gags find their way to the screen: witness Lam Suet running around with a knife in his butt-cheek. A perfunctory conclusion seems to indicate Johnnie To and co-writer Yau Nai-Hoi knew that returning to subtlety and measure after a patch of cartoonish excess would simply not have worked.

Long Story Short: Three is a delightfully tense, playful and clever little thriller that entertains and stimulates, despite an unfortunate final-reel fall into cartoonish excess. ***1/2