Will tried a casual, “How’s it going?”

The man didn’t respond. A nervous look twisted his features before he turned toward the exit, dragging the little girl behind him.

Will’s peripheral vision tracked the man leaving the bathroom. At the last minute, the man jerked the girl by the arm and practically flung her into the concourse.

Definitely not right.

Will waited a few seconds before following them. He peered around the corner of the exit and saw the man glancing nervously over his shoulder. Was he looking for his wife? Was he just irritated? Was something else going on?

The concourse was filled with the usual travelers dragging suitcases and pillows along the tile floor. Will weaved in and out of them, hunching down because his height made him stick out among most of the crowd. He saw the man heading toward the escalator that led down to the interterminal train. Will pulled out his cell phone as he followed. He tried to scroll to Faith Mitchell’s number, but the phone didn’t respond.

Minesweeper.

Will cursed as he stuck the phone back into his pocket.

What would he tell his partner, anyway? That a man was being curt with his child in the bathroom? That the man didn’t look like the type to make sure the pink trim on his daughter’s collar exactly matched the pink on her Hello Kitty shoes?

If she was his daughter.

Will could see the top of the girl’s head. Her hair was light, almost yellow. The man’s hair was an unnatural brown, possibly dyed. Did that mean he wasn’t the father? Will hadn’t grown up with brothers and sisters, but he knew that the color of your hair could darken as you grew older. Will knew from the few photos he had of himself as a kid that his sandy-brown hair had started out nearly white.

Besides, the man could be her stepfather.

Whoever he was, he didn’t take much care with the girl. At the bottom of the escalator, he wrenched her up by the arm, pulling her off the last two stairs, jerking her toward the train that led to the other concourses.

“Hey!” a woman shouted in protest, but the man was already heading toward the first car on the train. There were two sets of doors. He used the far set, standing close to the exit, which meant he’d be one of the first people off.

Will could hear the familiar announcement warning that the train was about to depart. He pushed past the couple in front of him, hoping he looked like a normal, hurried traveler as he bolted toward the first car. Will used the second set of doors. A quick jump at the last minute got him inside before the final announcement came.

The crowd shifted as the train pulled away from the C concourse. The car was full. Will looked up at the display that showed the train’s progress. There were three more stops before baggage claim and the exit.

Will tried to be unobtrusive as he searched for the man and the girl. A group of Delta pilots and flight attendants were clustered in the center of the car. Couples and single business travelers were packed tightly around them. Most of the occupants were looking down at their iPhones and BlackBerries. Will found the man at the front of the car. He was still standing directly in front of the doors.

The brown hair made sense now. It was a wig. The thick black glasses were probably fake, too. The man slid them up his nose as he stared at his watch. And then he looked down at his side. Will guessed he was looking at the girl. There was nothing like compassion on his face. Just anger, tinged with what looked like anxiety.

Will knelt down, pretending to tie his shoe. He peered past a woman’s leg and saw the girl. Blonde hair like straw. Pale cheeks. Deep blue eyes with tears streaming down.

She looked straight at Will, and he felt like a knife was stabbing into his chest. She was obviously terrified.

Or was she just scared because she was in a busy airport, surrounded by strangers? Was she going to a funeral? Was she visiting a sick relative?

Will stood. He’d been stuck on toilet duty for three days. Maybe he was creating a circumstance where none existed. Maybe being a cop had made him too suspicious.

Or maybe he was right.

Will turned his back to the man and child. The pilot beside him was checking her email.

“Hey,” Will said, keeping his voice low. Her look said she thought he was going to try to hit on her, but Will pulled out his badge, keeping it shielded in his hand so that the whole train wouldn’t see. “I need your phone.”

She handed it to him without question. Will knelt down again, pretending to tie his shoe. He waited for the crowd to shift, then took a picture of the little girl. He stood to capture the man’s image, but the train jerked to a stop. The doors opened. The Delta crew got off. There were only a handful of people between Will and the man now.

“You coming?” one of the flight attendants asked.

The pilot waved him off, saying, “Be right there. I forgot my flight plan.”

The flight attendant didn’t seem to buy the explanation, but the people crowding in on the train cut him off. The announcement came again, a tinny woman’s voice warning them that the train was about to depart. Will glanced up at the display. They were two more stops away from the main terminal. Will dialed a familiar phone number and sent the picture of the little girl to Faith Mitchell, his partner. He handed the phone back to the pilot. “Thank you.”

She responded with a nod, taking the phone. He saw her scan the car with thinly disguised curiosity. Most of the Delta pilots had trained in the Air Force. They were as proficient at combat as they were at landing a 747. The woman looked ready to back him up, though Will was hard-pressed to think of a legal justification for detaining the man.

The girl could be the man’s daughter. Granddaughter. Stepchild. There didn’t have to be a funeral or a sick relative. She could simply be tired and cranky from a long flight. For that matter, so could the man. Lots of people took their anger out on their kids. It was hardly a surprising occurrence.

The train slowed for the A concourse. Again, there was the usual flow in and out of passengers. The pilot gave Will an apologetic shrug before getting off the train. She glanced back at him before rolling her flight case toward the opposite train.

The doors closed. Will could feel someone staring at him. He counted off a few seconds, but he still felt scrutinized. After a few more seconds, he tried to casually look back. His eyes met the man’s. There was a steeliness there now—no anxiety. No worry.

The train slowed again. The T concourse. Will stepped toward the doors and stared at his own reflection in the glass. His suit and tie made him look like every other passenger in the airport. Except for his lack of a suitcase. Will didn’t even have a briefcase for cover.

He took out his cell phone and pretended to scroll through numbers. Faith was probably calling back the Delta pilot right now, wondering why the woman had sent her a photograph of a child. Will was seized by an overwhelming sense of futility. There was nothing about the man’s actions that indicated anything was wrong. Lots of children cried for no reason. Lots of children wanted to go home, especially after a long flight.

The doors slid open. The crowd shifted to leave before the announcement reminded them that baggage claim was the next stop. Will got off the train. He kept his eyes on his phone as he walked. He heard the doors close, the train lurch forward. He could feel the man watching him, and looked up at the last minute. The man stood in the middle of the car, feet apart to counteract the movement. His hand was gripping the girl’s arm. The corner of his mouth went up in a knowing smile.