Tale of a social reformer or just a glorified thug?

Hundreds of people gather in a Bronx building, hands pressed together, with thumbs, index and pinkie fingers extended. As their leader preaches unity and nonviolence, he pauses. The crowd feverishly chants “Amor de Rey” -- “King’s Love.”

The scene is from the HBO documentary “Latin Kings: A Street Gang Story,” and though it looks like a spiritual gathering, prosecutors say it was nothing of the sort. In 1996, Antonio “King Tone” Fernandez became the “Inca,” or leader, of the Almighty Latin King and Queen Nation. And though Fernandez insisted he was reforming the violent gang into a social movement, he is now serving a prison sentence.

The fall of King Tone and the ripples it sent through his organization are traced in this riveting, troubling 90-minute movie, produced, directed and videotaped by Jon Alpert. It premieres tonight at 9:30.

Alpert spent more than a year following the black-and-gold-clad Latin Kings. Though King Tone and others joke about how they might harm Alpert, they grant him plenty of access. (It’s not noted in the film, but the group has some media savvy; ABC News once gave cameras to King Tone and his inner circle to tape their lives.)

The film shows the last hours of freedom King Tone had before pleading guilty to drug conspiracy charges in 1999. The scenes unfold without voice-over narration; instead, intertitles provide background. This being HBO, there is a lot of unexpurgated language. What emerges is a multilayered portrait of a man who, despite his public bravado, sings Barney songs to his daughter and has his regrets.

“Latin Kings” raises questions of its own, however. If King Tone is to be believed, the government locked up someone who was turning a gang into a positive force. If the D.A. is correct, the movie could easily be seen as glorifying a thug. “Latin Kings” tries to play it down the middle. But even as it seeks to strip the veneer off King Tone’s life, it also does a fair job of glamorizing it, complete with a rap soundtrack.