A dark-eyed young woman with an ornate neck tattoo caught Hala’s gaze from across the room. She held it for several seconds and then looked away, ostensibly taking in the enormous bull elephant that dominated the space between them.

Hala stopped to regard the display, then looked back. Again, the girl was staring. Was she from The Family? Or was this just Hala’s imagination working too hard?

“Tariq?” she said.

“I see her,” he said. “Go. I think she wants to talk.”

He kept his position while his wife worked her way slowly around the room, never losing sight of the stranger. She was Saudi, presumably, but dressed like an American college student. Ripped jeans, a peasant blouse, scuffed clogs. On her shoulder she carried a brightly colored Guatemalan bag. It appeared to be full. With books? Or maybe a bomb? For here? For now?

As Hala reached the back of the gallery, the girl came over and spoke to her.

“Excuse me,” she said. “Do you know where the reptile hall is?”

Her perfect American accent was a surprise. Had this one been recruited stateside? Or, Hala suddenly wondered, was this maybe not what she’d thought? Was this girl with the police?

“I’m sorry,” she answered. “I don’t know. I’m not from here.”

“Maybe I could take a look at your map?”

When the girl pointed at the brochure Hala had carried from the hotel, any last doubts left her. “Of course,” she said, and handed it over.

The girl unfolded it on top of her bag and studied it for several seconds while a stream of waist-high children in school uniforms ran past, squealing out ridiculous laughter having something to do with the elephant’s tusks.

“Here it is,” she said finally. “Reptiles. This is what I want to know more about.”

When she refolded the map and handed it back, something flat and hard was inside that hadn’t been there before. Hala looked down to see the silver edge of a disk tucked into the folds of laminated paper. It sent a quickening sensation up her spine.

“Thanksalot,” the girl said in a familiar American singsong style. She smiled vacantly, then turned and walked away without once looking back.

“No,” Hala said, too quietly to be heard by anyone but herself. “Thank you. And thank Allah.”

POLICE WORK ISN’T usually about surprises. It’s more about routines. This was completely different. Something incredibly strange was going on, not all bad, necessarily, but strange. It was like no case I had ever worked before, or come across.

One of the special agents in Ned Mahoney’s unit at the Bureau called me on Monday morning and said he wanted to send over some files.

“Files?” I said. “Like, just any files?”

“Some reinterviews from the Coyle investigation we’d like to get your take on,” he said.

After days of being totally shut out, this request felt random, even disorganized on the part of the Bureau.