An important story for our era: How the American Dream went wrong for two immigrants, and the nightmare that resulted.

The facts of the tragedy are established: On April 15, 2013, two homemade bombs fashioned from pressure cookers exploded near the finish line of the Boston Marathon, killing three people and wounding 264 others. The elder of the brothers suspected of committing this atrocity, Tamerlan Tsarnaev, died in the ensuing manhunt; Dzhokhar will stand trial in January 2015. What we don’t know is why. How did such a nightmare come to pass?

This is a probing and powerful story of dislocation, and the longing for clarity and identity that can reach the point of combustion. Bestselling Russian-American author Masha Gessen is uniquely endowed with the background, access, and talent to tell it. She explains who the brothers were and how they came to do what they appear to have done. From their displaced beginnings, as descendants of ethnic Chechens deported to Central Asia in the Stalin era, Gessen follows them as they are displaced again, from strife-ridden Kyrgyzstan to war-torn Dagestan, and then, as émigrés to the United States, into an utterly disorienting new world. Most crucially, she reconstructs the struggle between assimilation and alienation that ensued for each of the brothers, fueling their apparent metamorphosis into a new breed of homegrown terrorist, with their feet on American soil but their loyalties elsewhere—a split in identity that seems to have incubated a deadly sense of mission. Like Dave Cullen’s Columbine, this will be the enduring account of an indelible tragedy.