Hard Truth (Anna Pigeon, #13)

Just three days after her wedding to Sheriff Paul Davidson, Anna Pigeon moves from Mississippi to Colorado to assume her new post as district ranger at Rocky Mountain National Park, where three young girls have disappeared during a religious retreat. Two of the children emerge a month later, clad only in filthy underwear and claiming to remember nothing of the intervening weeks. The girls are traumatized but forge a bond with the pair of campers who discovered them - a wheelchair-bound paraplegic and her elderly aunt.
With the reappearance of the children comes an odd and unsettling presence in the park, a sense of disembodied evil and unspeakable terror: small animals are mercilessly slaughtered and a sinister force seems to still control the girls. As Anna investigates, she finds herself caught up in the machinations of a paranoid religious sect determined to keep their secrets and the girls sequestered from law enforcement and psychiatric help.
Following the trails of the many suspects, especially that of the cult's intense youth group leader, Anna discovers the force which has destroyed the children's minds. Here in the park, evil has the eyes of a visionary and the soul of the devil. Anna will discover the truth-even if it kills her.