A few children started crying, and their mothers rushed to comfort them. But others clapped their hands in awe.

“They look real,” Marini whispered. “It’s amazing.”

He was enchanted.

Teresa shrugged. “It’s a residue of pagan fertility cults, a celebration of the winter solstice that survived the advent of Christianity,” she said. “The legend says that on the night of Saint Nicholas, the Krampus would wander around in search of children who had misbehaved. They were the saint’s own servants, acting on his command. I suppose that was their way of sidestepping the Inquisition.”

Marini looked at her.

“You always manage to boil everything down to some logical cause. It’s really quite extraordinary,” he said.

She kept her eyes on the worshippers, whom she couldn’t see as anything other than what she’d just described to Marini.

“I detect a note of sarcasm,” she muttered.

“On the contrary. I’m genuinely impressed.”

“Oh, shut up, Marini.”

The demons began to mingle with the crowd, and the calm that had previously reigned made way for a hectic euphoria.

“What’s Parisi doing?” Teresa barked. “Why aren’t the lights back on yet?”

She was getting nervous. She kept thinking that the killer might be behind one of those masks, already stalking his next victim. Her team had vetted each devotee and had also checked them as they prepared for the ceremony, but now she felt as if she hadn’t really seen any of them before.

The square was a whirlwind of activity threatening to submerge her at any moment. Faces, smells, sounds, lights . . . everything was moving too quickly, becoming a blur. Teresa closed her eyes.

She was afraid she wouldn’t be able to complete the mission. She felt as if she’d aged years in the space of a few hours.

Calm down, she told herself. Breathe.

The suspect was out there somewhere, beyond the anxiety that clouded her vision. To find him, she had to push herself beyond her own limits. She tried to remember his features, studying the image in her mind. She focused on its every detail until she was familiar with them all.

When she felt ready, she opened her eyes once more. This time she didn’t let the urgency to find him overwhelm her, but worked methodically, keeping her own gaze under a tight leash. Using landmarks to guide her, she checked the men milling about at the stalls and at the corners of the square, then looked over at those who were lingering outside the restaurants. Then, she divided the tide of moving people into streams and studied each one as it drifted past her.

Method, she thought. All I need is method.

That was how she found the one she was looking for out of the hundreds of faces around her.