‌We’d been airborne for about twenty minutes when Briggs and Sterling started briefing us on where we were going—and why.‌

“We have a case.” Sterling’s voice was calm and cool. Not too long ago, she would have insisted that there was no we, that minors—no matter how skilled—had no place in an FBI investigation.

Not too long ago, the Naturals program had been restricted to cold cases.

A lot had changed.

“Three bodies in three days.” Briggs picked up where Sterling had left off. “Local police didn’t realize they were dealing with a single UNSUB until an initial autopsy was done on the third victim this morning. They immediately requested FBI assistance.”

Why? I let the question take hold. Why didn’t the police connect the first two victims? Why request FBI intervention so quickly after victim number three? The busier my brain was, the easier it would be to keep it from going back to the body the police had found.

Back to a thousand and one memories of my mother.

“Our victims seem to have very little in common,” Briggs continued, “aside from physical proximity and what appears to be our UNSUB’s calling card.”

Profilers used the term modus operandi—or MO—to refer to the aspects of a crime that were necessary and functional. But leaving a calling card? That wasn’t functional. It wasn’t necessary. And that made it a part of our Unknown Subject’s signature.

“What kind of calling card?” Dean asked. His voice was soft and had just enough of a hum in it to tell me that he was already shifting into profiling mode. It was the tiny details—what the calling card was, where the police had found it in each case, what, if anything, it said—that would let us understand the UNSUB. Was our killer signing his work, or delivering a message? Tagging his victims as a sign of ownership, or opening a line of communication with the police?

Agent Sterling held up a hand to stave off questions. “Let’s back up.” She glanced over at Briggs. “Start from the beginning.”

Briggs gave a curt nod, then flipped a switch. A flat screen near the front of the plane turned on. Briggs hit a button, and a crime scene photo appeared. In it, a woman with long, dark hair lay on the pavement. Her lips had a bluish tint. Her eyes were glassy. A sopping wet dress clung to her body.

“Alexandra Ruiz,” Agent Sterling narrated. “Twenty-two years old, college student majoring in pre-occupational therapy at the University of Arizona. She was found about twenty minutes after midnight on New Year’s Eve, floating facedown in the rooftop pool at the Apex Casino.”

“The Apex Casino.” Sloane blinked several times. “Las Vegas, Nevada.”

I waited for Sloane to tell us the square footage of the Apex, or the year it was founded. Nothing.

“Pricey.” Lia filled the void. “Assuming our victim was staying at the Apex.”

“She wasn’t.” Briggs brought up another photo, inset to one side of Alexandra’s, this one of a man in his early forties. He had dark hair with just a dusting of silver. The photo was a candid one. The man wasn’t looking at the camera, but I got the distinct feeling that he knew it was there.

“Thomas Wesley,” Briggs told us. “Former internet mogul, current world poker champion. He’s in town for an upcoming poker tournament and rented the penthouse suite at the Apex, with exclusive access to the rooftop pool.”

“I’m guessing our boy Wesley likes to party?” Lia asked. “Especially on New Year’s Eve?”

I stopped examining Thomas Wesley’s picture as my eyes were drawn upward toward Alexandra’s. You and some friends thought it would be a blast to spend New Year’s Eve in Vegas. You got invited to a party. Maybe even the party. Her dress was turquoise. Her shoes were black, high-heeled. One heel had been snapped off. How did you break your heel?

Were you running? Did you struggle?

“Did she have any bruises?” I asked. “Any sign that she’d been held under the water?”

Any sign that she fought back?

Agent Sterling shook her head. “There were no signs of a struggle. Her blood alcohol level was high enough that police assumed it was an accident. Tragic, but not criminal.”

That would explain why the police hadn’t connected their first two victims. They hadn’t even realized Alexandra was a victim.

“How do we know it wasn’t an accident?” Lia swung her legs over the side of her seat, letting them dangle off.

“The calling card.” Dean and I answered at the exact same time.

I turned my mind from Alexandra to the UNSUB. You made it look like an accident, but left something to tell the police that it wasn’t. If they were smart enough, if they connected the pieces of the puzzle, they’d see. See what you were doing. See the elegance in it.

See how clever you are.

“What was it?” I voiced the question Dean had asked earlier. “What did the UNSUB leave?”

Another click from Briggs, another picture on the screen, this one a close-up of a wrist. Alexandra’s. Her arm lay palm-up on the pavement. I could see the veins beneath her skin, and just above them, on the outside edge of her wrist, were four numbers, inked into her skin in fancy script: 3213. The ink was dark brown, with a slight orange tint to it.

“Henna,” Sloane offered, playing with the edge of her sleeve, judiciously avoiding eye contact with the rest of us. “A dye derived from the flowering plant Lawsonia inermis. Henna tattoos are temporary and, at any given time, less common than permanent tattoos by a factor of about twenty to one.”

I could feel Dean beside me, processing this information. His gaze was locked onto the picture, as if he could will it to tell him the full story. “The tattoo on her wrist,” he said. “That’s the calling card?”

You’re not just leaving messages. You’re leaving them inked onto the bodies of your victims.

“Is there any way to get a time stamp on the tattoo?” I asked. “Did he mark her, then drown her, or drown her, then mark her?”

Briggs and Sterling exchanged a look. “Neither.” Sterling was the one who answered the question. “According to her friends, she got the tattoo herself.”

As we processed that information, Briggs cleared the screen and brought up a new photo. I tried to look away, but couldn’t. The corpse on the screen was covered in blisters and burns. I couldn’t tell if the victim was male or female. There was only one patch of unmarred skin.

The right wrist.

Briggs gave us a close-up.

“4-5-5-8.” Sloane read out loud. “3-2-1-3. 4-5-5-8.” She stopped talking, but her lips kept moving as she went over and over the numbers.

Meanwhile, Dean and I were staring at the photograph.

“Not henna this time,” he said. “This time I had the numbers burned into my target’s skin.”

My preferred pronoun for profiling was you. I talked to the killer, to the victims. But when Dean slipped into an UNSUB’s head, he imagined being the killer. Doing the killing.

Given who and what his father was—and the way Dean couldn’t shake the fear that he’d inherited some trace of monstrousness—that didn’t surprise me. Every time he profiled, he faced that fear head-on.

“I suppose you’re going to tell us victim number two burned the numbers into his own arm?” Lia asked Briggs. She did a good job of sounding unaffected by the gruesomeness of what we were seeing, but I knew better. Lia was an expert at masking her true reactions, showing only what she wanted the world to see.

“In a manner of speaking.” Briggs brought up another picture, side by side with the wrist. It looked like some kind of wristband. Set back into the thick material it was made of were four metal numbers: 4558, but flipped— a mirror image of the numbers on the victim’s skin.

Agent Sterling enlightened us. “Fire-retardant fabric. When our victim caught fire, it heated the metal, but not the fabric, leaving a legible brand underneath.”

“According to our sources, the victim received the bracelet with a parcel of fan mail,” Briggs continued. “The envelope it was mailed in is long gone.”

“Fan mail?” I said. “And that makes the victim…who?”

Another picture flashed onto the screen in response to my question, this one of a twentysomething male. His face was striking and gaunt, sharp angles offset by violet eyes—probably contacts.

“Sylvester Wilde.” Lia let one of her feet fall to the floor. “Modern-day Houdini, illusionist, hypnotist, and jack-of-all-trades.” She paused, then translated for the rest of us. “He’s a stage magician—and like most of his kind, an excellent liar.”

From Lia, that was a compliment.

“He had a nightly show,” Briggs said, “at the Wonderland.” “Another casino.” Dean mulled that over.

“Another casino,” Agent Sterling confirmed. “Mr. Wilde was in the midst of his evening performance on January second when he—to all appearances—accidentally set himself on fire.”

“Another accident.” Dean bowed his head slightly, his hair falling into his face. Already, his concentration was so intense, I could see it in the lines of his shoulders, his back.

“Or so the authorities believed,” Agent Briggs said. “Until…” One last picture, one last victim.

“Eugene Lockhart. Seventy-eight. He was a regular at the Desert Rose Casino. He came once a week with a small group from a local retirement home.” Briggs didn’t say anything about how Eugene had died.

He didn’t need to.

There was an arrow protruding from the old man’s chest.