Jehane Noujaim’s documentary won the audience award at last year’s Sundance before she’d even finished it. But then, the revolution it records wasn’t yet finished either. An essential chronicle of the recent and very rocky political history of Cairo’s Tahrir Square, Noujaim’s project proceeds with the clear-eyed understanding that the public ouster of Egyptian president Hosni Mubarek in 2011 really was just the beginning. Getting deep inside the chaos, The Square frames up a cross-section of its participants, whose actions and eloquent appraisals Noujaim and her brave crew collect. These subjects include Ahmed Hassan, an energetic and passionate young activist; actor Khalid Abdalla, the star of The Kite Runner and a de facto English spokesperson for the revolutionaries; and Magdy Ashour, a politically conflicted member of the Muslim Brotherhood. Of the three, Hassan seems most to enjoy or at least to sense an opportunity in having a camera pointed at him, whereas the professional performer Abdalla treats even his most off-the-cuff appearances with the solemnity of duty. (It’s the latter who observes, “The battle is not rocks and stones. The battle is in the images.”) Meanwhile Ashour, who was tortured under Mubarek and now sometimes is taunted by his secular friends, politely embodies the tormented soul of an entire society. Noujaim’s film rousingly reveals that the maintenance of hope for a sustainably democratic Egypt requires, above all, tirelessness — of the activists, and of the filmmaker herself.