Orphans — Jean Simon

Now that her mother is dead, unmarried Rae Downing believes she is alone in the world...until the phone rings and a woman's voice speaks the impossible: "Rae, this is your sister."

Rae knew she'd been adopted but never dreamed a sister existed. With her boyfriend Gary, Rae flies to the frigid winter of Minnesota, to finally meet Josie, her long-lost sibling. But Rae soon discovers there's more than one secret in her past. A third sibling exists, a strange and dangerous completion to a terrible triangle...

Suddenly Rae is swept up in a harrowing scenario of terror, lust, and cold-blooded murder: and she finally understands that together these triplets possess a mysterious power of dangerous proportion...and deadly force.