Several minutes later, our food was deposited on the table. With great effort, Sloane let go of my hand and pulled her gaze away from the happy threesome, just as Aaron slid into the empty seat at the table to join his family.

His family. Not hers.

I tried to catch Sloane’s eye, but she wouldn’t look at me. She concentrated all of her attention on the sushi in front of her, carefully disassembling it and dividing each roll into its parts. Avocado. Salmon. Rice.

At the bar, Camille and Tory finished their drinks. As they gathered their possessions and turned toward us, I noticed two things. The first was the thick silver chain Camille wore looped multiple times around her neck.

The second thing was Aaron Shaw noticing Camille.

Five minutes after Camille Holt and Tory Howard exited the restaurant, Aaron excused himself from his family’s table. Half an hour after that, Mr. Shaw carried his delighted little girl through the room to get a cherry at the bar. As father and daughter returned to their seats, I saw Shaw register Sloane’s presence. He never faltered, never altered the pace of his stride.

But my gut told me he recognized her.

This was a man who oozed power and control. Based on the son he’d raised, I was willing to bet he knew everything that went on in this casino. Aaron might not know that Sloane is your daughter, but you do. You’ve always known.

Beside me, Sloane looked so nakedly vulnerable that my eyes stung for her.

“Sloane?” Michael said quietly.

She forced her lips upward in a valiant attempt at a smile. “I’m digesting,” she told Michael. “This is my digesting face, that’s all.”

Michael didn’t press her on it, the way he would have if it were Dean or Lia or me. “And what a pleasant digesting face it is,” he declared.

Beside me, Sloane developed an intense interest in her lap. By the time dessert arrived, she was moving her finger back and forth over the surface of her skirt. It took me a moment to realize that she was tracing out numbers.

3213. 4558. 9144.

I wondered how much of Sloane’s fascination with numbers had arisen during moments like this one, when numbers were easy and people were hard.

“Well,” Lia said, snagging a bite of mint ice cream with her spoon. “I, for one, am ready for bed. I’m also considering joining a nunnery and have no interest whatsoever in hitting the shops.”

“I’m not going shopping with you,” Dean said darkly.

“Because you’re afraid I might try to introduce actual colors into your wardrobe?” Lia asked innocently.

Beside me, Sloane was still going, number after number drawn with the tip of her finger on the surface of her skirt.

“How many shops are there in Las Vegas?” Lia said. “Do you know, Sloane?”

The question was a kindness on Lia’s part—though she wouldn’t have liked me thinking of her as kind.

“Sloane?” Lia repeated.

Sloane looked up from her lap. “Napkins,” she said.

“Not going to lie,” Michael put in. “I had no idea that was a number.”

“I need napkins. And a pen.”

Judd fished a ballpoint pen out of his pocket and handed it to her. Dean grabbed some cocktail napkins off the bar.

3213. 4558. 9144. The second that Dean handed her the napkins, Sloane scrawled out the numbers, each sequence on its own napkin.

“It’s not three,” she said. “It’s thirteen. He cut off the one. I don’t know why he cut off the one.”

He as in the UNSUB. Sloane wasn’t a profiler. She’d never been trained to use I or You.

“That’s why I didn’t see it before.” Sloane added a vertical line to the left of the first number. “It’s not 3213,” she said. “It’s 13213.” She moved on to the next napkin. “4558. 9144.” With the pen, she began grouping the numbers into pairs. “Thirteen. Twenty-one. Thirty-four. Fifty-five. Eighty-nine.” Finally, she circled the last three digits. “One hundred and forty-four.” She looked up from the napkins, her eyes bright, as if she expected this to clarify everything. “It’s the Fibonacci sequence.”

There was a long pause. “And the Fibonacci sequence is what exactly?” Lia asked.

Sloane frowned, her forehead wrinkling. Clearly, it hadn’t occurred to her that the rest of us might not know what the Fibonacci sequence was. “It’s a series of numbers, derived from a deceptively simple formula where each subsequent integer is calculated by adding together the two previous numbers in the series.” Sloane sucked in a breath, but babbled on. “The Fibonacci sequence appears throughout the biological world: the arrangement of pinecones, the family tree of honeybees, nautilus shells, flower petals….”

Across the room, a man wearing a suit and an earpiece walked straight past the hostess. Even if I hadn’t spent the past few months interacting with FBI agents, I would have recognized him as security.

People walk differently when they’re the only ones in the room carrying a gun.

“The Fibonacci sequence is everywhere,” Sloane was saying. The man in the earpiece approached Mr. Shaw and bent to whisper something in his ear. The casino owner’s face remained carefully controlled, but when Michael followed my gaze, he must have seen something I didn’t. His eyebrows shot up.

“It’s beautiful,” Sloane continued. “It’s perfection.”

I met Michael’s eyes across the table. He held my gaze for a few seconds, then he raised one finger. “Check, please.”