Ten Thousand Several Doors = Mistress of Lost River — Mary Shura Craig

Lori could no longer claim the name she bore all her life; and if she became the new and strange personality everybody insisted she was, she would inherit the prosperous Lost River Ranch that would make her a very rich and powerful young woman.

In her quest for an identity, Lori runs headlong into a web of murder, mistaken identity and romantic intrigue in an exciting search for her birthright.