The Ghost of Christmas Past (Molly Murphy Series #17)

Semi-retired private detective Molly Murphy Sullivan is suffering from depression after a miscarriage following her adventure in San Francisco during the earthquake of 1906. She and her husband, Daniel, are invited for Christmas at a mansion on the Hudson, and they gratefully accept, expecting a peaceful and relaxing holiday season.

Not long after they arrive, however, they start to feel the tension in the house’s atmosphere. Then they learn that the host couple's young daughter wandered out into the snow ten years ago and was never seen again. Molly can identify with the mother's pain at never knowing what happened to her child and wants to help, but there is so little to go on. No ransom note. No body ever found. But Molly slowly begins to suspect that the occupants of the house know more than they are letting on.

Then, on Christmas Eve, there is a knock at the door and a young girl stands there. "I'm Charlotte," she says. "I've come home."