Paul Greengrass, who made the brilliant “United 93” about the “third plane” of 9/11 (as well as the fact-based thrillers “Bloody Sunday” and “Captain Phillips”), brings a similar degree of dramatic urgency to his recreation of another recent mass tragedy. The event in question is the terrorist assault that lone-wolf Anders Behring Breivik undertook on July 22, 2011, setting off a bomb outside the office of Norway’s Prime Minister Jens Stolfenberg in Oslo that killed eight people.

That, however, was but the first stage of Breivik’s plan. While authorities concentrated on the explosion, he drove in the guise of a policeman to Utøya Island northwest of Oslo. Armed with automatic weapons, he proceeded to kill sixty-nine people and wound more than a hundred more, most of them youngsters attending a summer camp run by AUF, the youth organization affiliated with Stolfenberg’s Labor Party, before SWAT teams arrived to disarm him.

The first part of Greengrass’ film, based on Åsne Seierstad’s 2015 book “One of Us,” is a recreation of the horrendous acts of Breivik (Anders Danielsen Lie), captured by the director and his able crew—most notably cinematographer Pål Ulvek Rokseth, production designer Liv Ask and editor William Goldenberg—in the harrowing semi-vérité style familiar from his previous docu-dramas, a style grimly realistic and more restrained than that adopted by Peter Berg for such fact-based action films such as “Deepwater Horizon.” There is naturally a good deal of violence depicted, but Greengrass is never sensationalist in staging it, often showing it indirectly or from a distance.

The graphic exception is his focus on Viljar Hanssen (Jonas Strand Gravli), a buoyant seventeen-year old who is attending the camp along with his younger brother Torje (Isak Bakli Aglen). The children of Christin Kristofferson (Maria Bock), a local Labor Party politician running for mayor of their northern hometown, and biologist Sveinn Are Hanssen (Thorbjørn Harr), they run for their lives as Breivik attacks, eventually taking refuge on a ledge overlooking the sea. He finds them, however, and wounds Viljar horribly as Torje escapes.

From this point, “22 July” shifts into the aftermath of the tragedy, dividing into two complementary plot strands. One involves the interrogation and trial of Breivik, who is assigned liberal attorney Geir Lippestad (Jon Øigarden) to act as defense counsel—a role that the lawyer hardly relishes but accepts out of a sense of duty despite his feelings about his client and the effect on his family. He attempts to construct an insanity plea, but is undercut by public pressure from the families of the victims, and by Breivik’s insistence that he have the opportunity to explain his motives in open court as a call to other like-minded ideologues to take up arms as soldiers in the war he’s begun to cleanse Europe of infectious foreign influences and the multicultural policies the Labor Party represents. His assault on the youth camp, he says, was to purge the next generation of the party’s leadership.

That story thread—which also touches on the grief-wracked Stolfenberg’s efforts to grapple with his government’s failure to prevent the atrocity and Lippestad’s efforts to mount a defense by enlisting Breivik’s hyper-anxious mother (Hilde Olausson) and other like-minded extremists to testify—is juxtaposed with the desperate efforts of emergency-room personnel to save Viljar as his family looks on, and the boy’s torturous rehabilitation—he has been blinded in one eye, has lost several fingers and is left with a severe limp, while inoperable fragments near his spine could shift and kill him. He is also troubled by the fact that his younger brother is keeping his distance, obviously blaming himself for coming away physically unscathed while Viljar acted to protect him from harm.

Viljar struggles not only to regain the will to live, but to steel himself to testify in Breivik’s trial. He’s aided in this by another survivor, Lara Rashid (Seda Witt), whose sister died in the attack and comes to visit the boy in the hospital, becoming a kind of sympathetic confidante as he readies himself reluctantly to face the terrorist in the courtroom. The film leads up to the sorrowful but determined accounts of the July day that Lara and Viljar give, somber testimony that nonetheless represents renewed determination in the face of unspeakable bigotry and horror; and to Breivik’s incarceration in solitary confinement.

Greengrass presents his account of this Norwegian counterpart to America’s 9/11 with a steady gaze that avoids exploitation while honestly depicting both the malignancy behind the terrorist’s actions and the heroic efforts his victims had to muster to overcome the trauma and pain he caused. The film undoubtedly leans toward sentimentality in its treatment of the survivors, but as with his portrayal of the violence early on, Greengrass pulls back before the film descends into melodrama, and with a major assist from an excellent cast—Lie is effectively odious, and Gravli exceptional in his portrait of a shattered young man—he manages to achieve, as with his previous efforts in this vein, a film that is profoundly moving without becoming maudlin.

“22 July” is obviously not an easy picture to watch, but it is a painfully truthful account of how fanaticism can suddenly rupture the placidity of modern life, requiring both reason and resilience to deal with the physical and psychological damage.