No Angels for Christmas by Petie McCarty

Child psychologist Rachel Kelly isn’t quite sure how to handle the situation with her newest client—a six-year-old boy who says he can talk to angels and one is coming to help Rachel. She already has her hands full of trouble this Christmas season, and things quickly take a turn for the worse when a stalker crashes Rachel’s Christmas party and takes her young clients hostage.
Police negotiator, Lt. Jake Dillon, walked away from his fiancée Rachel when she suddenly balked at having kids. His kids. Yet when the hostage crisis erupts, Rachel calls Jake first. Now he has a choice to make—stand back and wait for the cavalry to save Rachel or step in and try to save her himself. Time is running out, and Jake may be their only chance for rescue.
Unless Rachel’s little angel-spying client is telling the truth…