One of the visual motifs of the stark and shocking Lao Shi (Old Stone) is a cigarette burning in the dark. As the movie's taxi-driving protagonist inhales, the tip pulses red like a warning beacon. It signals danger on the road.

The hazard is explained casually in the opening scene, in which Lao Shi (Chen Gang) waits while listening to a radio report about a driver who hit someone, but didn't kill him. Rather than be responsible for the victim's medical costs, the driver backed up and ran over him. In China, life can be cheaper than hospital bills.

The radio news is a true story, and much else in Old Stone is real as well. Writer-director Johnny Ma, who was born in Shanghai but moved to Toronto at 10, used immersive techniques to make his first feature. He spent months in Guangde, the grungy small city where the story is set, to learn about the place and its people. Until the film switches its tone in the final minutes, cinematographer Leung Ming-kai shoots in a handheld documentary style, following Lao Shi as if he doesn't know where he's going.

Ma, an admirer of the Dardennes Brothers, used non-professional actors for most of the smaller roles. (The director himself has a cameo.) Although Ma wrote dialogue, he encouraged the cast performers to render it in their own words.

The story begins three months before the first scene. Lao Shi, whose name means "Old Man Stone" but also sounds like the Mandarin term for "honest," is driving a drunken passenger to the airport. The man grabs Shi's arm, causing the cabbie to hit a motorcyclist, Li Jiang (Zhang Zebin). An ambulance is called, but doesn't arrive, so Shi takes the victim to the hospital. There he's required to sign an agreement to pay for emergency care for Li, who ends up on a life support in a coma that could bankrupt his benefactor.

Shi honors his commitment to pay, much to the outrage of his wife, Mao Mao (veteran actress Nai An, also the movie's executive producer). She runs a day-care center she plans to expand, and has big hopes for the couple's 'tween daughter, who seems embarrassed by her old-fashioned father. Compassion for strangers is not part of Mao Mao's plan.

While she consults a lawyer, Shi turns detective. He contacts Li's wife, and eventually finds the man who caused the accident. His upscale status is evident from the item he left behind in Shi's taxi: an iPhone.

No one will take responsibility, and ultimately Shi feels he must stage a fateful confrontation. Now Old Stone shifts from docudrama to black-hearted thriller, powered by a spare, percussive score.

Ma is hardly the first director to treat the lives of people outside China's economic boom as crime stories. His parable is in the tradition of such movies as 2003's Mang jing (Blind Shaft), which is part murder mystery, part exposé of China's notoriously lax mining industry.

Occasionally, the movie depicts the burning of "spirit money" to help finance the afterlife of departed ancestors. This practice is not simply an expression of filial piety; well-funded ghosts are supposed to grant good fortune to their descendants.

For all its ugly self-interest, Old Stone is also beautiful, and not just in its use of red lights in black night. There are also insets of deep-green forests buffeted by wind, agitated yet serene. The scenery suggests the enduring things that are forgotten during a money quest that's anything but spiritual.

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