A touch of betrayal

This is told from the point of view of Grant (Tillie and Jessica's skeptic brother) who lives in tents with no modern conveniences in Africa near a tribe that he is studying. The heroine is Alexandra Prescott who is a fabric designer from New York looking for design inspiration from the wilds of Africa. They meet at the airport and she mistakes him for a derelict. He's there to pick up Mama Hannah who is the African woman who raised him and his sisters. He helps her get to her hotel and goes on his way. Alexandra find more is wild in Africa than she could have imagined when she gets a cable that her bank account is empty and then another guest tries to strangle her. She escapes and in the heat of the desert can only think of getting to Mama Hannah and Grant. But the killer guest is more than just a random occurrence and Alexandra finds herself hunted by a professional. Grant after finding her in near heat stroke finds himself in the midst of things as her protector.