The side door where Farid Ahmed wheels himself into the Al Noor mosque opens into a small room adjacent to the main prayer hall. On most days, Farid continues through that room so he can better hear the imam speak. But on a Friday afternoon in March, he sees a man there who he knows is sick.

Farid knows this because he knows everyone, or almost everyone, who worships at Al Noor, the largest mosque in the little city of Christchurch, on the south island of New Zealand. For 20 years, Farid and his wife, Husna, have taught children and adolescents at the mosque how to be proper Muslims and gracious citizens, which are, in fact, the same thing. He is not a credentialed scholar of Islam but rather an exceedingly gentle homeopath from Bangladesh, so the lessons are less religious dogma than practical applications of charity and kindness and respect. When a child understands that to be a good Muslim I have to be kind, he believes, then we don't have to think about cruelty.

The man Farid sees in the small room has cancer. Farid stops to speak with him, to check on his health and offer a few words of comfort. Husna is already inside, and Farid intends to stay only a few moments. But then the imam is preaching, talking about how people can find strength in communal righteousness. Farid thinks it would be rude to wheel his chair around during the sermon. He decides to wait until the imam is finished, then move into the main hall to pray.

In the alley next to Al Noor, an Australian man is jerking through a nine-point maneuver to get his Subaru turned around and aimed toward the street. There are three long guns on the passenger side and a rifle wedged between his right leg and the door. Each is covered in white graffiti, slogans and obscure names, some written in Cyrillic. Fife-and-drum music is playing, an old military song, like the soundtrack to a grade school history lesson.

The Australian is recording himself—or rather, recording what he sees—via a camera attached to his head that's feeding video to the internet. He began doing so not quite six minutes earlier. He is wearing a costume of dark camouflage clothing and kneepads and fingerless green gloves because he imagines himself to be a commando. Early that afternoon, he allegedly emailed a 74-page document to media outlets and government offices purporting to explain the undeclared war into which he had enlisted himself, though one could easily reduce his reasoning to an index card: He does not like brown people moving into countries that in recent history have been populated predominantly by white people.

“Remember, lads,” he'd said when he started his car, “subscribe to PewDiePie.”

That is not a revolutionary slogan but a catchphrase popular among the many millions of adolescent fans of a Scandinavian with a comedic YouTube channel that is best known, in one of the more pointless exercises of internet fame, for simply once having had more subscribers than any other YouTube channel. (It also is a phrase said Scandinavian has since asked people to stop saying.) The Australian apparently has spent many hours crawling around online, his understanding of the world curated by chat rooms and search-engine algorithms. “You will not find the truth anywhere else,” he wrote in his document. He also described himself as a fan of several racist mass murderers—Anders Behring Breivik, who killed 77 people in Norway; Dylann Roof, who shot to death nine people in a South Carolina church—and wrote that he admires Donald Trump as “a symbol of renewed white identity and common purpose,” though not as a political leader. His greatest influence, he wrote in a burst of either incoherence or epic trolling, was right-wing American carnival barker Candace Owens. “Though I will have to disavow some of her beliefs,” he wrote, “[because] the extreme actions she calls for are too much, even for my tastes.”