A Darker Place — Laurie R. King

A respected university professor, Anne Waverly has a past known to few: Years ago, her own unwitting act cost Anne her husband and daughter. Fewer still know that this history and her academic specialty alternative religious movements have made her a brilliant FBI operative. Four times she has infiltrated suspect communities, escaping her own memories of loss and carnage to find a measure of atonement. Now, as she begins to savor life once more, she has no intention of taking another assignment. Until she learns of more than one hundred children living in the Change movement's Arizona compound....

Anne soon realizes that Change is no ordinary community and hers is no ordinary mission. For, far from appeasing the demons of her past, this assignment is sweeping her back into their clutches ... and to the razor's edge of danger.