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.
Used availability for Mabel Esther Allan's The Sign of the Unicorn
January 1975 : UK Hardback