Siddharth, a powerful drama about working-class life in India, opens with a heartwarming scene: The protagonist, New Delhi handyman Mahendra (Rajesh Tailang), gently waves goodbye to his 12-year-old son, Siddharth, after putting him on a bus for a monthlong sojourn far away.

Is Siddhu, as everyone calls the precocious cricket fanatic, going to a sports camp? Is he staying at the seashore with cousins?

Afraid not. The boy is headed 325 miles away to a trolley factory in Ludhiana, where he'll work full-time and live in a dorm with other teen laborers.

Mahendra is a chain-wallah, someone who walks door to door offering to fix zippers. Business has been slow, and he really needs the extra income his son can bring in.

As he tells Siddhu on the phone, the entire family is proud of the boy for his sacrifice.

Mahendra, wife Suman (Tannishtha Chatterjee), and their girl, Pinky (Khushi Mathur), wait in vain in their windowless, one-room cinder-block home for Siddhu to return. He never does.

The police treat the disappearance as an abduction, telling Siddhu's parents that hundreds of kids regularly are sold into forced labor, used as sex workers, or killed for organ harvesting.

Cowritten and directed by Canadian Richie Mehta (Amal), Siddharth is a spare, lean, and decidedly unsettling account of the ugly reality of child labor and child abduction in India.

It's a real film about a real problem: No Liam Neeson-like hero arrives, guns blazing, to help his abducted child. Nor is the film filled with endless weeping, therapeutic navel-gazing, and soppy, wall-to-wall strings and piano.

Mehta's no-nonsense verite style makes the film all the more shattering. So does his ability to present characters who have complex, conflicting moralities. Mahendra, for one, is neither all good nor all bad for sending his little boy to work.

Chided by a cop for breaking India's child labor laws, he forcefully announces, "Why would I have a son, if not to work him?"

Yet it's clear the man deeply loves his son and would do anything for him.

So he spends the rest of the film looking for his beloved boy, traveling hundreds of miles to track down the most tenuous clues. The stories of the lost children he meets on his travels - runaways, laborers, sex workers - will break your heart.

Siddharth ***1/2 (out of four stars)

Directed by Richie Mehta. Rajesh Tailang, Tannishtha Chatterjee, Anurag Arora, Amitabh Srivasta. Distributed by Zeitgeist Films.

In Hindi with English subtitles.

Running time: 1 hour, 36 mins.

Parent's guide: No MPAA rating (adult subjects, disturbing themes).

Playing at: Ritz Bourse.