In the gathering darkness, Nicki and Christine swam quietly toward the Mary Celeste II . The water was as black as ink around them, and Nicki tried not to think of the living things that might be passing by her in the warm water. They reached the stern of the boat where the overhead light on deck threw shadows in the water. Nicki lifted her face mask. "Are you going to climb up, or should I?" Christine's mouth fell open and her eyes bugged. "Behind...