On a gray January Sunday in 1972, in Derry, Northern Ireland, British soldiers opened fire with live ammunition on unarmed, peaceful demonstrators, killing 13. Shocking and visceral, writer/director Paul Greengrass’s documentary-style re-creation of the horrifying events of that day pulls no punches, bluntly depicting the powder-keg atmosphere of the city: the disquieting enthusiasm of the British troops on the streets, tired of taking the brunt of local ire and itching for a fight; the disdain of the British major general on the scene (Tim Pigott-Smith, weaselly perfection), dismissing civil-rights protestors as “hooligans”; the zeal of the people of Derry, led by the local MP (James Nesbitt, energetic and passionate), unwilling to back down in their own city. One of their grievances: the policy of the occupying British of internment of Irish citizens without trial — the unexpected parallels to today’s political climate give the film far greater impact. The uninitiated won’t find a larger context in which to place the events depicted, and some may find the working-class Derry accents nearly impenetrable, but seek it out anyway. This is a stunning achievement, a disturbingly powerful film. It’ll be hard to beat as one of the year’s best.