If the 20th century is any evidence, the human race is better at memorializing tragedy than preventing it. We build monuments to our remorse, hold solemn ceremonies, and vow “Never again,” until it’s time to build the next memorial. Just this month, Bosnia commemorated the tenth anniversary of Srebrenica, the worst massacre in Europe since WWII. Under guard of Dutch Blue Helmets, the Muslim enclave was easily overrun by Serb paramilitaries, who then perpetrated the mass execution of 8,000 Bosnian Muslim men and boys. The remembrance elicited the obligatory expressions of solidarity from the rest of the world. No doubt the same heartfelt gestures can be expected a decade or two from now in memory of Darfur.

One of the lessons that Lt. Gen. Romeo Dallaire learned in his capacity as the commander of the U.N. mission to Rwanda is that the international community—what a vague, utopian concept that is—is impervious to moral shaming. At the helm of a ragtag force during the height of the 1994 genocide, a desperate Dallaire sought to embarrass the U.N. into action with strident appeals through the media. But, as he notes in Peter Raymont’s documentary Shake Hands with the Devil, “Africa had nothing to sell, nothing to buy”—the worst kind of nothing imaginable. Rwanda was abandoned to its fate as Dallaire was to his, and another tragedy for future commemoration was under way.

A hagiography of a reluctant hero, Shake Hands with the Devil fixes its gaze on Dallaire, who has emerged as one of our great humanitarian advocates. The movie shares its title with Dallaire’s book from 2004, but the subtitles for each reveal the crucial differences between the two. Dallaire’s book is an anatomy of “The Failure of Humanity in Rwanda”; the movie goes for the therapeutic—and more cinematic—route, “The Journey of Romeo Dallaire.” While certainly still worthwhile, the documentary could’ve actually paid better tribute to Dallaire had it devoted more attention to Rwanda and genocide, rather than lingering on the general’s personal story of torment and redemption.

You can’t blame Raymont for focusing on Dallaire. Articulate, straightforward, unpretentious, thoughtful, sincere, and genuinely modest, the man is a dream subject. A career soldier in a family of military lifers, Dallaire was appointed to head the U.N. peacekeeping mission in Rwanda in June 1993. (Dallaire candidly admits that his initial response was, “Rwanda, that’s in Africa, isn’t it?”) Fourteen months later, he would leave Rwanda a broken man, an impassioned yet impotent witness to the massacre that killed 800,000 Tutsis and moderate Hutus in 100 days. In the years following, Dallaire spiraled—he attempted suicide, was issued a medical release from the Canadian Armed Forces, was diagnosed with post-traumatic stress disorder, and attended therapy and took medication for his condition. The book and the movie are testaments to his rejuvenation, but also reminders that, for Dallaire, there may never be such a thing as full recovery.

The movie has an irresistible peg: It chronicles Dallaire’s return to Rwanda in 2004, on the occasion of the genocide’s tenth anniversary. Raymont follows Dallaire as he makes his way around a country that has plagued his imagination for years, interspersing his odyssey with the usual array of interviews with experts and officials. Shake Hands with the Devil also contains some of the most heartbreaking and terrible footage from the genocide itself, images that, in their novelty, underscore the extent to which Western publics have been shielded from the tragedy. Despite the poignancy of the reality, Raymont overdramatizes Dallaire’s agony, a lack of restraint signaled by the hackneyed use of Barber’s “Adagio for Strings” over a close-up of Dallaire in the opening minutes. That the movie happens to be about a protagonist who seems congenitally averse to self-aggrandizement only highlights Raymont’s needless inflation of its import.

Raymont’s documentary is at its strongest when it sits back and lets the enormity of the Rwandan massacre mushroom without prompting. At one graveyard for the victims, Dallaire encounters a man whose entire family was wiped out. Dallaire listens to his story intently and can only summon a heartbroken expletive in response. Later, Raymont stumbles upon a telling metaphor: When Dallaire returns to visit the U.N. compound in Kigali, over which he presided during those apocalyptic days, the security guard stops him at the gate and leaves him waiting for a long time. The peeved Dallaire is eventually fetched by an apologetic official from headquarters, who explains away the confusion with a shrug: “You know, the U.N.”

Yes, Dallaire knows—he can tell you stories about the U.N. Dallaire’s mission in this new phase of his life is to force a change in the way the international community deals with humanitarian crises. In Samantha Power’s A Problem from Hell—a good companion piece to Dallaire’s memoir and a great book in its own right—the world’s response to genocide is depicted as a fugue of indifference and impotence. Dallaire emerges as one of the unfortunate heroes of that book, a man of conviction steamrolled by a bureaucracy of cretins and cowards. Shake Hands with the Devil is a cri de coeur from someone who had to witness the consequences of their apathy and was lucky (and, perhaps, unlucky) enough to survive it.

Dallaire’s experience sheds light on how the problem of genocide confounds easy political definitions. The liberal claim to Samaritan compassion notwithstanding, the general’s positions actually put him at odds with branches of leftist orthodoxy. For one, Dallaire is unambiguous about the responsibility of powerful nations to intervene in the internal troubles of other countries—a belief that puts him squarely against the Chomskyian distrust of U.S. interventionism that courses through some factions of the left. (Lest we forget, the NATO intervention in Kosovo, which prevented the genocide of ethnic Albanians, was opposed not just by conservative isolationists but anti-imperialist pacifists as well.)

Dallaire’s stance is also a rebuke to those who have made a fetish of multilateralism. If there is one thing that Rwanda taught us, it is that the U.N., as currently envisioned, is institutionally incapable of dealing with genocide. The U.S. bears no small amount of blame for the U.N.’s toothlessness, but the rest of the world certainly is not absolved of responsibility. As Dallaire observes in his book, “While most nations agreed that something should be done, they all had an excuse why they should not be the ones to do it.” The U.N., we are reminded, is really nothing more than a collection of countries each seeking to advance its own self-interest. That the U.N. offers them a chance to do so in a civilized context is admirable—but consensus, Dallaire reminds us, does not define morality.

One of the more shaming moments in Shake Hands with the Devil presents footage of Bill Clinton’s visit to the country long after the killing stopped. Apologizing after the fact, Clinton’s I-feel-your-pain empathizing never seemed more hollow. Dallaire’s purity of purpose and complete lack of narcissism make him a stark counterpoint. Rejecting the label of hero, Dallaire emerges as something less, and something more—a martyr for our sins. For years, he has suffered the nightmares and the agonies that, by all rights, should be ours too. Raymont’s movie may not give us much in the way of prescriptions, but it does offer the sting of a conscience that refuses to rest, and that’s no small thing.