A Time to Die — Hilda Lawrence

Just as he encountered murder while off duty in Blood upon the Snow, detective Mark East once again finds his vacation interrupted by a mystery. Perhaps it was a mistake to return to the same small town. On his last visit, the streets of Crestwood lay buried in snow. This time, blazing heat overwhelms the sleepy resort community. In the cool of evening, locals and summer visitors gather for a church supper. Afterward, one guest fails to return to the hotel, but East refuses to take an interest, reasoning that an attractive young woman might have any number of more interesting prospects.
But everyone insists that it's not like Mary Cassidy to suddenly disappear, citing her pleasant ladylike behavior and her kindness to a motherless child. As East's host, Sheriff Perley Wilcox, uncovers further details about the missing woman, the detective gradually becomes more and more drawn into the case until his concern is captured by a grotesque discovery in the town's well. The suspense builds as East investigates Mary's background and learns that the retiring gentlewoman wasn't at all what she seemed to be -- and that time is running out for the next victim!