then, soft and comforting without judgment or pity. Zoe had to look away a moment.
“I’m working on this case,” Zoe started.
“I know all about it,” Shelley told her. “This whole pi thing. What you know, I know. Well, go on. Ask me, Z.”
Zoe shifted, shading her eyes as she looked out to sea. “I need your opinion,” she said. “Did we arrest the right guy? Or is the killer still out there?”
She didn’t emphasize the danger inherent in the wrong answer. Shelley already knew. She had paid for it with her life once already.
“You already know the answer.” Shelley looked at her gravely for a long moment. “What did Dr. Applewhite tell you? You’re relying too much on the numbers. On the numerical representation of pi.”
Zoe remembered what Dr. Applewhite had said. Keep it simple. Stop overcomplicating things just because you are able to see all of the layers.
The layers she could see were not always visible to everyone else.
Zoe nodded slowly. “I already have the answer.”
“That’s what I said,” Shelley said, laughing lightly. The sound was caught on the gentle breeze, drifting away from them like a soft cloud.
“Pitsis is not the killer,” Zoe said, thinking out loud, words spilling out of her like water. “He sees pi just as the number that it is. It is an irrational number, and he wants it to be rational. That’s all. A mathematical problem.”
“Not enough of an obsession to drive him to murder,” Shelley said, raising her coconut and taking a sip. “Just to drive him to drink.”
“The killer sees pi as a representation of more than just an irrational number,” Zoe went on. She was on a roll now. “For him, it’s something much more. Not just a number at all.”
“That’s right,” Shelley said. She picked the book up off her stomach, finding her page and propping it open. “Now, it’s not that I’m not pleased to see you, Z. But don’t you have something to do?”
“Yes,” Zoe told her. She took one last fleeting look at the island, at Shelley in her hammock, and then closed her eyes. “I do.”
CHAPTER TWENTY SEVEN
It was late, but Zoe couldn’t just go to sleep and forget about the case. If the wrong person was behind bars, that meant that the killer was still out there. He could be stalking his next victim even now. He might have killed again already. Zoe couldn’t wait for the morning.
She slipped out of her motel room, locking the door behind her, and hesitated, looking at the next room over. Flynn’s room. The lights were out. He was expecting a big day in the morning, and it had been a long few days already; Zoe guessed he was probably asleep already. She didn’t need to wake him up, did she? It wasn’t as though they were really partners. Not permanently. And Zoe could handle this on her own.
She refused to address the thought lurking in the periphery of all this: that if she investigated this alone while Flynn stayed behind, she would be the one potentially plunging into danger. He would be safe. The door locked, dreams filling his head. He wouldn’t be at risk of dying.
Thankfully, though, they had picked up two sets of keys for the rental car, so that either of them could drive it at any given time, even if the other one was far away. Which meant that Zoe didn’t have to wake him in order to set off. She got behind the wheel and started the engine, setting up the GPS to take her back to Syracuse University.
It was entirely possible that there would be no one there at this time of night, but it didn’t particularly matter. The library would be open twenty-four hours a day to accommodate students, who had a time-honored tradition of studying all night long right before a test and spending the whole of the rest of the time not studying at all. Zoe only hoped that she would be able to find the information she needed without the help of the staff, who would be tucked up at home themselves at this hour.
With the roads almost empty in the darkness, it was easier for Zoe to concentrate. She could see the circumference of the twin beams of light that shot out from the car’s headlights, and she could calculate all sorts of things to do with that, but this time it didn’t stop her from seeing the road itself. She counted her breaths in sets