Birthmark killer

The two dogs ripped open the bull shark's stomach and out spewed chunks of human flesh. samantha "sam" volare stared down at the cabo, mexico boat ramp at the remains of her prize-winning fish and pointed. "that's a man's tennis shoe with a foot still inside." upon closer inspection, she observed one of the pieces of skin had a discoloration-a duck birthmark. none of the shark fishing contestants wanted her to dig deeper into the identity. back home in sandpoint, idaho, she couldn't let it go. she needed to find out who her shark ate. would the bizarre happenings and two other deaths discourage her? would the person responsible kill her before she discovered who the birthmark belonged to? could one of sam's friends or any of the men who were the other contestants have something to do with the pieces of human flesh found inside her fish?