About the time that a female French relief worker falls in love with the leader of a rogue militia, wrapping up in his arms just as he plans to unleash urban war against the leaders of rival factions, the documentary “Ghosts of Cité Soleil” officially veers away from anything resembling sanity. Here, it seems, even one of the international aid officials sent to help a distraught people is seduced by the violent testosterone running wild and unchecked. All hope truly is lost.

In a triumph of access above all else, the directors Asger Leth and Milos Loncarevic somehow managed to worm their way into the confidences of extremely dangerous men, and into the lives of their sizeable street armies, capturing an extraordinary world of violence and death from within. Think of this as the true-to-life “City of God,” where more than once you have to shake your head and remind yourself that this is indeed the story of a major city filled with real people; nothing short of a true-life hell on Earth.

Hell, it turns out, is Cité Soleil, the slum of Haiti’s Part au Prince, what the United Nations has not so subtly dubbed “the most dangerous place on Earth.” Here, abject poverty and lawlessness is ruled by the “chimeres,” roaming street gangs who control this endless sea of rubble (housing some 500,000 people) with iron fists. Allegedly armed and supported by President Jean-Bertrand Aristide before his ouster, the chimeres — or ghosts — were essentially the unchecked de-facto authorities of Cité Soleil through 2004. Each gang aggressively recruited new members, equipped them with a wide array of weapons, and worked to prove, both to their adversaries and average citizens, that it was the most powerful chimere of them all.

The closer “Ghosts of Cité Soleil” brings us to the reality on the streets, the more remarkable it seems that Messrs. Loncarevic and Leth (son of Jorgen Leth, introduced to many American audiences through Lars Von Trier’s “The Five Obstructions”) were able to survive the carnage. For months, they lived with the chimeres and gradually gained access to two of the proudest and most arrogant leaders, each presiding over his own neighborhood.

The first, who calls himself 2pac, is a charismatic charmer who spends much of his time riding through town in his pimped-out SUV; when he’s not suiting up for battle, he writes original hip hop songs. The second leader is Bily, 2pac’s brother, who seems smarter but less refined. While the rapping 2pac seems to enjoy the celebrity that comes with his position of power, Bily is more committed to rising up through the ranks of the Lavalas political party in hopes of one day succeeding Mr. Aristide.

In classic Shakespearean form, the two thugs have sensitive sides that contrast sharply with their violent impulses and abilities, and both confess secret dreams to the camera when no one is listening. In one scene, the filmmakers get 2pac on the phone with the prominent Haitian-American musician Wycleaf Jean — who wrote the film’s score and signed on as producer — and the gang leader sings a tune for the master, which Mr. Jean enjoys. There’s no denying the tragedy of this moment, of watching a young man so humbled and honored by the compliments of his idol, yet still painfully aware that his time on this earth, as the leader of a chimere, is sure to be short.

In such a tense and dangerous world, overflowing with testosterone and guns, violence seems all but assured. Young members of the chimeres aggressively try to move up the ranks, older veterans try to exert control over their subordinates, indiscriminant gunfire leads to retaliations, and then retaliations lead to more retaliations. The fatal spark in this pressure cooker is the forced removal of Mr. Aristide and the installation of a new leader who declares war on the chimeres, backed by French and American troops. As the outsiders begin to patrol Cité Soleil, the dynamic quickly changes: Suddenly it’s not just the gangs fighting among themselves, but also chimeres going up against Haitian troops and international forces. In the blink of an eye, the untouchable chimeres have become the preferred target of the day. Just as 2pac hopes to break out of this world for good, the violence starts to spin out of control.

Early on, Messrs. Loncarevic and Leth successfully give us a sense of the surge of energy these thugs feel when they are called to arms, wrapping us up in their closed world and helping us to see it on their terms. When Lele, a French aid worker, falls into 2pac’s arms, we gradually, though sadly, come to understand why; he is something akin to celebrity and royalty in Cité Soleil, a place that requires him to pick up a gun or die. Here’s a perfect example of the way cinema can convey what words cannot: We feel his anxiety, we sense his isolation, and we walk away from Messrs. Loncarevic and Leth’s document with not just the understanding, but the heartbreaking assuredness that these are doomed souls in a sad, forgotten place.

ssnyder@nysun.com