The best true-crime stories use a particular event as a key to unlock a world, and Patrick Radden Keefe’s latest work of investigative nonfiction, London Falling, does just that. At first glance, I winced a bit at the book’s title. This is the story of a 19-year-old boy named Zac Brettler, who in 2019 plunged to his death from the balcony of a fifth-floor apartment overlooking the Thames into the river below. Using a pun off an old Clash song seemed an overly cheeky way to refer to such a tragedy. In the end, however, Keefe’s choice makes perfect sense....