The Sign of the Unicorn — Mabel Esther Allan

Taking vacation in Paris to forget a broken romance? That's what Julia Conway did. And, she met Martin and Annette, brother and sister, who are entangled in an affair of blackmail, stolen paintings and murder. So, why did she help them? Why did she follow the trail to a 200-year-old haunted mansion? Will she lose her life because she was so friendly to Annette? This is an exciting read for teens.