His arithmetic awareness and his inherent cynicism about financial institutions always compelled him to check his balance every time he withdrew cash. He always remembered to deduct the ATM fees and every quarter he remembered to add in the bank’s paltry interest payment. And despite his suspicions, he had never been ripped off. Every time his balance came up exactly as he predicted. He had never been surprised or dismayed.

Until that morning in Portland, where he was surprised, but not exactly dismayed. Because his balance was more than a thousand dollars bigger than it should have been.

Exactly one thousand and thirty dollars bigger, according to Reacher’s own blind calculation. A mistake, obviously. By the bank. A deposit into the wrong account. A mistake that would be rectified. He wouldn’t be keeping the money. He was an optimist, but not a fool. He pressed another button and requested something called a mini-statement. A slip of thin paper came out of a slot. It had faint gray printing on it, listing the last five transactions against his account. Three of them were ATM cash withdrawals that he remembered clearly. One of them was the bank’s most recent interest payment. The last was a deposit in the sum of one thousand and thirty dollars, made three days previously. So there it was. The slip of paper was too narrow to have separate staggered columns for debits and credits, so the deposit was noted inside parentheses to indicate its positive nature: (1030.00).

One thousand and thirty dollars.

1030.

Not inherently an interesting number, but Reacher stared at it for a minute. Not prime, obviously. No even number greater than two could be prime. Square root? Clearly just a hair more than thirty-two. Cube root? A hair less than ten and a tenth. Factors? Not many, but they included 5 and 206, along with the obvious 10 and 103 and the even more basic 2 and 515.

So, 1030.

A thousand and thirty.

A mistake.

Maybe.

Or, maybe not a mistake.

Reacher took fifty dollars from the machine and dug in his pocket for change and went in search of a pay phone.

He found a phone inside the bus depot. He dialed his bank’s number from memory. Nine-forty in the West, twelve-forty in the East. Lunch time in Virginia, but someone should be there.

And someone was. Not someone Reacher had ever spoken to before, but she sounded competent. Maybe a back-office manager hauled out to cover for the meal period. She gave her name, but Reacher didn’t catch it. Then she went into a long rehearsed introduction designed to make him feel like a valued customer. He waited it out and told her about the deposit. She was amazed that a customer would call about a bank error in his own favor.

“Might not be an error,” Reacher said.

“Were you expecting the deposit?” she asked.

“No.”

“Do third parties frequently make deposits into your account?”

“No.”

“It’s likely to be an error, then. Don’t you think?”

“I need to know who made the deposit.”

“May I ask why?”

“That would take some time to explain.”

“I would need to know,” the woman said. “There are confidentiality issues otherwise. If the bank’s error exposes one customer’s affairs to another, we could be in breach of all kinds of rules and regulations and ethical practices.”

“It might be a message,” Reacher said.

“A message?”

“From the past.”

“I don’t understand.”

“Back in the day I was a military policeman,” Reacher said. “Military police radio transmissions are coded. If a military policeman needs urgent assistance from a colleague he calls in a ten-thirty radio code. See what I’m saying?”

“No, not really.”

Reacher said, “I’m thinking that if I don’t know the person who made the deposit, then it’s a thousand and thirty bucks’ worth of a mistake. But if I do know the person, it might be a call for help.”

“I still don’t understand.”

“Look at how it’s written. It might be a ten-thirty radio code, not a thousand and thirty dollars. Look at it on paper.”

“Wouldn’t this person just have called you on the phone?”

“I don’t have a phone.”

“An e-mail, then? Or a telegram. Or even a letter.”

“I don’t have addresses for any of those things.”

“So how do we contact you, usually?”

“You don’t.”

“A credit into your bank would be a very odd way of communicating.”

“It might be the only way.”

“A very difficult way. Someone would have to trace your account.”

“That’s my point,” Reacher said. “It would take a smart and resourceful person to do it. And if a smart and resourceful person needs to ask for help, there’s big trouble somewhere.”

“It would be expensive, too. Someone would be out more than a thousand dollars.”

“Exactly. The person would have to be smart and resourceful and desperate.”

Silence on the phone. Then: “Can’t you just make a list of who it might be and try them all?”

“I worked with a lot of smart people. Most of them a very long time ago. It would take me weeks to track them all down. Then it might be too late. And I don’t have a phone anyway.”

More silence. Except for the patter of a keyboard.

Reacher said, “You’re looking, aren’t you?”

The woman said, “I really shouldn’t be doing this.”

“I won’t rat you out.”

The phone went quiet. The keyboard patter stopped. Reacher knew she had the name right there in front of her on a screen.

“Tell me,” he said.

“I can’t just tell you. You’ll have to help me out.”

“How?”

“Give me clues. So I don’t have to come right out with it.”

“What kind of clues?”

She asked, “Well, would it be a man or a woman?”

Reacher smiled, briefly. The answer was right there in the question itself. It was a woman. Had to be. A smart, resourceful woman, capable of imagination and lateral thinking. A woman who knew about his compulsion to add and subtract.

“Let me guess,” Reacher said. “The deposit was made in Chicago.”

“Yes, by personal check through a Chicago bank.”

“Neagley,” Reacher said.

“That’s the name we have,” the woman said. “Frances L. Neagley.”

“Then forget we ever had this conversation,” Reacher said. “It wasn’t a bank error.”

Reacher had served thirteen years in the army, all of them in the military police. He had known Frances Neagley for ten of those years and had worked with her from time to time for seven of them. He had been an officer, a second lieutenant, then a lieutenant, a captain, a major, then a loss of rank back to captain, then a major again. Neagley had steadfastly refused promotion beyond sergeant. She wouldn’t consider Officer Candidate School. Reacher didn’t really know why. There was a lot he didn’t know about her, despite their ten-year association.

But there was a lot he did know about her. She was smart and resourceful and thorough. And very tough. And strangely uninhibited. Not in terms of personal relationships. She avoided personal relationships. She was intensely private and resisted any kind of closeness, physical or emotional. Her lack of inhibition was professional. If she felt something was right or necessary, then she was uncompromising. Nothing stood in her way, not politics or practicality or politeness or even what a civilian might call “the law.” At one point Reacher had recruited her to a special investigations unit. She had been a big part of it for two crucial years. Most people put its occasional spectacular successes down to Reacher’s leadership, but Reacher himself put them down to her presence. She impressed him, deeply. Sometimes even came close to scaring him.

If she was calling for urgent assistance, it wasn’t because she had lost her car keys.

She worked for a private security provider in Chicago. He knew that. At least she had four years ago, which was the last time he had come into contact with her. She had left the army a year later than he had and gone into business with someone she knew. As a partner, he guessed, not an employee.