Showing Shadow Woman by Thomas Perry

When her latest client, a Las Vegas gaming executive who has lost the trust of his criminally-connected bosses, asks for help, Jane Whitefield gets him out of town with a spectacular display of casino magic. Then she keeps her promise, gives up her dangerous trade, marries her loyal doctor, and settles down to live peacefully in upstate New York. As if. Fifty pages into Thomas Perry's third book about Whitefield--who uses a mixture of her Seneca ancestors' wisdom and a lot of modern muscle and computer smarts to make people in danger disappear--her client screws up. Jane's highly developed code of honour makes her leave her bridal bed to rescue him from an eerily psychotic Los Angeles couple who use everything from sex games to attack dogs to track him down. Previous paperbacks in this first-rate series are Vanishing Actand Dance for the Dead.