On a cold night in December, the members of a Hasidic anti-crime patrol called the Shomrim are summoned to a yeshiva dormitory in Crown Heights. There to break up a brawl, the Shomrim instead find themselves embroiled in a religious schism which has split the community and turned roommate against roommate, neighbor against neighbor. At the center of the storm is Aron Hershkop, the owner of an auto-repair business and the leader of the Shomrim. Hershkop watches as the NYPD builds a...