Lucky's Lady by Tami Hoag
When Serena Sheridan's grandfather vanishes into the vast and infamous swamps of Louisiana for no apparent reason, she feels compelled to abandon her successful career as a psychologist and go and find him. But Serena is deeply afraid of the hostile territory she is confronting and her only guide is the renegade Lucky Doucet, a dangerous Cajun who offers little hope of protection in the steamy Bayou swamps. However, determined to find her grandfather at whatever cost, she sets off with Lucky on a journey into the watery maze that will irrevocably change both their lives...