Dangerous Summer — Brenda Castle

Anya has been in love with Zack Anderson, her brother-in-law, from childhood. Since her sister's tragic death a year ago, Anya has only his secretary as a rival for his affections - and tensions mount when they stay together at Zack's villa in the south of France. But then the summer erupts into violence, and life at the Villa Donmarie becomes a nightmare when Anya realises someone she knows might be a double murderer. It might even be someone she loves...