When police in Rexburg, Idaho perform a wellness check on seven J.J. Vallow and his sister, sixteen-year-old Tylee Ryan, both children are nowhere to be found. Their mother, Lori Vallow, gives a phony explanation, and when officers return the following day with a search warrant, she, too, is gone. As the police begin to close in, a larger web of mystery, murder, fanaticism and deceit begins to unravel.

Vallow's case is sinuously complex. As investigators prod further, they find the accused Black Widow has an unusual number of bodies piling up around her.

WHEN THE MOON TURNS TO BLOOD tells a gripping story of extreme beliefs, snake oil prophets, and explores the question: if it feels like the world is ending, how are people supposed to act?