Behind the Shadows — Patricia Potter

In Patricia Potter's seductive and chilling novel of romantic suspense, a young woman trying to prove that she and an heiress were switched at birth steps into a privileged world where a killer is watching and waiting to silence her forever

Kira Douglas's mother, Katy, will die unless she receives a new kidney. Kira is the likely donor candidate . . . until blood tests reveal that she isn't Katy's biological daughter. If she isn't Kira Douglas, then who is she? And how can she save her mother? The only answer is to find Katy's true daughter by birth.
 
Kira's search leads to Leigh Howard, an heiress to a $50 million trust fund, and her formidable protector, Max Payton, a charismatic attorney who doesn't trust Kira or her theory that she and Leigh were accidentally switched at birth. When Kira's life is threatened, it becomes clear that someone doesn't want the truth to come out or allow Kira to lay claim to the legendary Westerfield fortune. Now Max is torn between his loyalty to Leigh and his powerful desire for the woman who has upset their privileged world. But he may be too late to stop a legacy of hate and greed that was set in motion decades ago -- and is about to come full circle.