What is the main conflict in Without Remorse by Tom Clancy?

After the death of his wife, Tish, John Kelly picks up a hitchhiker one day and takes her home to his island. He doesn't know of her history or that she is hooked on drugs. When he finds out, he nurses her back to health with the aid of some doctor friends he met. They set up an appointment with a police officer who he knows so the girl can tell her story and help the other women who are being held. But Kelly makes a mistake. Before the meeting, they drive around the neighborhood where the drug dealers were and are spotted. Kelly is shot and the girl is killed.