“How did you think this was going to go?” he asked, unable to keep the anger from his voice. “Did you think you and I would do police work together?” Gretchen’s psychopathic logic could be bewildering, but this was insane even by her standards. “We tried that, didn’t we?” Archie added. “Back when you said you were a consulting psychologist.” Back when she’d betrayed him, tortured him, left him in a medically induced coma for a month, destroyed his marriage. “Maybe no one ever made it official,” Archie said, “but you’re fired.” He looked Gretchen in the eye. “You let that girl die. You disturbed evidence. You didn’t do any of this as some deranged birthday present for me. You did it for fun, for your own satisfaction.” He could tell he was right by the defiance in her face. “Tell me something,” he said. “Back at the lake, when you were on top of me, what were you thinking about? Were you imagining him raping and murdering that girl?” Their faces were inches apart. “Did it excite you?”

Gretchen went rigid. For a moment Archie thought he had pushed her too far. But then the corner of her mouth turned up in a smile. She liked it when he could figure her out. She looked at him without blinking. Smirking like that, splattered with fake blood, she looked deranged.

“You’ll catch him for me,” she said with certainty. “You’ll have to.” Her eyes flashed with determination. “Remember, you’re a hero. This is what heroes do. She wasn’t his first kill. He knew what he was doing. He was organized. He knew what he wanted.”

Archie turned away and rubbed his face with both hands, trying to think. She was right. If she was telling the truth. Targeting a stranger, luring her to a killing ground, and then disposing of the body—these all indicated the work of a serial killer. If Gretchen hadn’t pulled Lisa Watson’s corpse up, they wouldn’t even know there’d been a murder. How many women had this man killed whose bodies hadn’t surfaced, who were maybe in the lake right now? If Gretchen was telling the truth. If. If. “I want to see Susan,” Archie said, turning back.

“Not yet,” Gretchen said. She ran her finger along the collar of his shirt and looked up at him coyly. “Ask me how we’re going to do it.”

Of course. Archie had forgotten whom he was dealing with. Gretchen Lowell always had a plan. “How are we going to catch him?” Archie asked.

Gretchen straightened his collar. Then she turned smartly and walked to the table and opened the laptop. “I know where he buried the knife,” she said over her shoulder. She threw Archie a smug smile. “A hundred cops just searched the island,” she said. “What do you think the odds are he’ll move it?”