There’s no denying the level of sheer cinematic craft in Johnnie To’s “Three,” a coiled-spring thriller that expertly ratchets up the tension before exploding in a breathtaking finale. It lacks any heart or humanity, but whether that matters will depend on your point of view.

The film is set at a Hong Kong hospital, where a crime boss named Sung (Wallace Chung) is wheeled into an emergency room on a gurney with a bullet wound to the head. He’s trailed by a bevy of cops headed by Ken Chen (Louis Koo), who describes the injured man as part of a gang caught in a robbery who was shot when he fired on police. Dr. Tong Qian (Vicki Zhao) takes on the case; she’s an ambitious, self-confident young surgeon, but has recently fumbled two operations—one has left a patient paralyzed, the other resulted in a burst aneurysm. Even her boss Dr. Fok (Eddie Cheung Siu-fai) worries that she’s pushing herself too hard and needs a rest. But she’s insistent that Sung needs immediate surgery to remove bullet fragments lodged in his brain.

But Sung, a smirking, cocky fellow who spouts smart-ass philosophical observations between bursts of maniacal laughter, adamantly refuses. He’s awaiting a rescue attempt by his crew, and in fact they’re already at work to launch an assault on the hospital, as one of Chen’s least capable officers, Fatty (Lam Suet), has come to believe, even though his effort to track down the perpetrators—mostly by humming a tune (actually the beginning of Mozart’s “Eine kleine Nachtmusik”) that he recalls from the robbery—are inept.

Chen, meanwhile, is determined to force Sung to reveal the whereabouts of his confederates, and it eventually becomes evident why: Sung’s wound wasn’t a response to his shooting at the cops, but the result of a gun being put to his head, and (perhaps inadvertently) fired, in an attempt to extract information from him. Chen’s anxious to keep his squad’s highly improper methods under wraps. Unfortunately Dr. Tong’s interference allows Sung’s gang to determine his whereabouts and plan accordingly. Chen foresees that, of course, and tries to manipulate the situation to his advantage: as the first hour of “Three” passes, both sides assemble virtual mini-armies prepared to do battle.

The clash that follows is a visual tour-de-force as bombs go off and bodies fly around, along with bullets and blood. It’s the sort of sequence that will invite frame-by-frame analysis by genre cultist, an amalgam of pinpoint choreography and whirling camerawork given special frisson by having actors miming slow motion while what’s occurring around them happens in real time. (It’s also accompanied by a pop tune in which the singer intones references to Confucius and Buddhism!) As if that weren’t enough, the shoot-out is followed by a vertigo-inducing scene of men hanging perilously from a building on a rope made of sheets and a fire-hose. In the midst of all the mayhem a mini-miracle occurs involving Tong’s paralyzed patient, whose tumble down a flight of stairs in a wheelchair looks frighteningly genuine.

There are stumbles in this visually dazzling entertainment that To has devised along with his production designer Bruce Yu, cinematographer Cheng Siu-keung and editor David Richardson. The camera often focuses on particular details—a lost bottle of medicine or a set of keys, for instance—that may be links in the plot Sung’s gang have concocted to free him, but their particular function isn’t made very clear. (Even that Mozart theme is arbitrary, and ultimately a dead end.) The persistent emphasis on peripheral characters—some of Chen’s squad, a gluttonous patient with a head injury whose dotty peregrinations are intended as comic relief—simply confuses things without adding any emotional layers of consequence. And the performances, even by the leads, are basically one-note, with Koo sternly impassive, Zhao attempting to disguise her insecurity under a mask of calm until Tong breaks, and Chung strutting petulantly even when lying down. None is a character of depth, and the actors do not try to plumb any.

But that’s of a piece with the film, which is little more than an exercise in action-oriented razzmatazz. Still, it succeeds on that level, and for many that will be sufficient.