In Cold Pursuit — Ursula Curtiss

Whilst in the Mexican town of Juarez, Mary and her cousin Jenny each encounter strange men, but neither of them realizes that one of these men is obsessed with revenge and murder. But which one?

The man in the blue car parked in the shadows down the road was spying on the woman he planned to execute. His mortally injured wife had described her--young, with short fair hair that cupped her head in a ruffle--this woman who had locked the door in her face, refusing her sanctuary from her killer-rapist. After his wife had died in surgery, the man identified his enemy as Mary Vaughan. He was wrong. Mary had not even heard of the tragedy, and she was not fleeing from his revenge. She was taking her eighteen-year-old cousin Jenny Acton to Juarez for a days to avoid a possible confrontation with Jenny's unsuitable and very resentful former fiance. Unfortunately word had been leaked to him that the Acton's had sent their daughter to Santa Fe where she would be well out of his reach. Now Jenny's mother telephoned from New York that the hot-tempered ex-fiance might suddenly descend on them.

Once on their way to Mexico, Mary was light-hearted with relief. Although Jenny pointed out that a blue car had been following them for a long time, she was not worried. It was only when they reached the hotel in Juarez that odd little happenings aroused her fears. Soon real danger followed these chilling portents.

Here is an absorbing novel about a bewildered woman who does not know who is threatening her life or why.