At two in the morning, a McDonald's in Upper Manhattan was still lit up and open for business.
In the innermost booth of the dining area, the three of them sat together. The professor sat across from Lin An, holding a cup of hot coffee, with a half-eaten hamburger in front of him.
Darnell had already finished two hamburgers and was working on his third serving of fries, crunching away. The sound was especially clear in the quiet restaurant.
Lin An held a cup of black coffee and sipped it unhurriedly, as elegant as a young nobleman.
The three of them stayed silent for a long time.
Darnell was busy eating, as if he'd starve to death if he slowed down. Lin An didn't feel like talking, while the professor was still trying to process everything that had just happened...
The kidnapping, the smoke bombs, the beating, the murder, and then, when the sirens sounded, the young man had led him out through the back door. They'd crossed three alleys and ended up at this fast-food restaurant.
Robert wondered why he'd run just now.
He was the victim. When the police arrived, he could have told them that four people had kidnapped him and that two young men passing by had rescued him.
And that would have been that... He was a professor at Columbia University. Four thugs dying for no particular reason was hardly a problem for him.
Why had he run?
[Because the old bastard cares about his reputation. I was his student in 2009.]
[How much does he care?]
[The old man's a leader in financial engineering. His reputation is his life. Once, he taught a class with his fly open. As soon as he noticed, he dismissed the class, then sent an apology letter to every student who'd been there.]
[Wow, that's caring about your reputation way too much.]
[So there's no way he'd let anyone find out he was kidnapped and almost raped by a guy. They'd laugh him out of academia.]
The professor took a deep breath, set down his coffee, and looked up at Lin An.
"Tell me. What do you want from me?"
Lin An lifted his coffee, took a sip, then set it down.
"I want to become your student."
The professor froze.
"What?"
"Your student."
Lin An repeated himself.
"A doctoral student under your name. I don't need to attend classes or have you supervise me. I just need a status... student status at Columbia University."
The professor stared at Lin An for five seconds, his brows furrowing.
His mind raced... A young man who'd killed four people without batting an eye was now asking to become his student?
Something was off.
There had to be a catch.
"What do you need student status for?"
The professor's voice turned cautious.
"Are you planning to use my reputation to launch some kind of financial project?"
He'd seen too many people like that... They'd attach themselves to him, use his resources, then set up shady financial products on Wall Street. When they made money, they'd call themselves his students. When things went wrong, they'd cut ties with him.
Not long ago, one of his former students had used his name to start a company on Wall Street. After he exposed him, the company went bankrupt.
Lin An shook his head.
"No."
He paused.
"I want to use my student status under your name to sort out my own status."
The professor didn't understand.
"What do you mean?"
Lin An leaned back in his chair and folded his hands on the table, fingers interlocked.
"I don't remember anything about my past, and I haven't found any identification. No passport, driver's license, Social Security card—nothing."
His tone was calm as he said what sounded like a true lie without the slightest change in expression.
"I'm probably undocumented. Without legal status in the United States, I can't do anything. So I want to become your student and get legal status."
The professor scratched his head, at a loss for words.
He'd lived for over sixty years and taught at Massachusetts Institute of Technology for more than thirty. He'd seen all kinds of students, but he'd never encountered anything like this.
A man had killed four people, then sat down and calmly said, "I want to be your student because I don't have ID."
This wasn't just absurd.
It was deranged.
The professor studied Lin An's face... young and handsome, with a faint smile on his lips and eyes as still as a dead pond.
He looked perfectly normal.
No, that wasn't right.
He looked too normal.
A normal person shouldn't act like this after killing someone.
The professor silently came to a conclusion about Lin An... This man was mentally ill.
The corner of his mouth twitched.
He wanted to say, "Are you crazy?" but he didn't dare.
The professor swallowed, picked up his coffee, took a big gulp, set it down, and cleared his throat.
"Uh... Mr.?"
"Just call me Lin An."
"Right, Lin An."
The professor adjusted his posture, trying to look more at ease.
"You said you want to become my student. You should know that becoming a doctoral student at Columbia University isn't that simple. You need an undergraduate degree, GRE scores, letters of recommendation, and an interview..."
"I know."
Lin An cut him off.
"But I feel like I'd make a good student. I'm qualified to become a doctoral student at Columbia University."
Darnell stopped chewing his fries, glanced at Lin An, then lowered his head and kept eating.
The Bullet Screen went wild.
[Hahahahahaha, streamer, what are you saying???]
["I feel like I'd make a good student."]
["I'm qualified to become a doctoral student at Columbia University."]
[Is this what they mean by "confidence at its peak"?]
[Columbia University: Who are you, exactly?]
[Streamer: I'm your daddy.]
[The professor's expression is killing me. His mouth keeps twitching.]
[Professor: I want to curse him out, but I'm afraid he'll kill me.]
[The professor must be thinking: This guy's a nutcase, but I can't say it out loud.]
Lin An ignored the Bullet Screen and looked at the professor, his smile unchanged.
The professor was silent for a few seconds, then nodded.
"Fine. Since you say so, I'll test you."
He spoke politely, like an elderly professor chatting with a student who'd caught his interest.
"What's your name?"
"Lin An."
"Is Lin An your Chinese name?"
"I think so."
"You think so?"
"I told you, I don't remember my past. I came up with the name Lin An myself."
The corner of the professor's mouth twitched again.
"All right, Lin An. Since you want to be my student, I'll ask you a few basic questions."
He thought for a moment, then asked,
"What's the fundamental theorem of calculus?"
The Bullet Screen started posting answers.
[The fundamental theorem of calculus: If a function f is continuous on the closed interval [a,b] and F is an antiderivative of f, then ∫_a^b f(x)dx = F(b)-F(a).]
[No, that's the second fundamental theorem.]
[The first fundamental theorem says: If f is continuous on [a,b], then F(x)=∫_a^x f(t)dt is differentiable on [a,b], and F'(x)=f(x).]
[Say both, just to be safe.]
Lin An glanced at the Bullet Screen, then looked up, his expression calm again.
"The fundamental theorem of calculus has two parts."
He began,
"Part one: If a function f is continuous on the closed interval [a,b], then the function F(x)=∫_a^x f(t)dt is differentiable on [a,b], and F'(x)=f(x)."
He paused.
"Part two: If f is continuous on [a,b] and F is any antiderivative of f, then ∫_a^b f(x)dx = F(b)-F(a)."
The professor's eyes widened slightly. He continued,
"In linear algebra, what are eigenvalues and eigenvectors?"
The Bullet Screen started posting again.
[Easy. This is from the first chapter of linear algebra. Watch this...]
Lin An repeated the answer from the Bullet Screen.
The professor's expression changed.
"What does the central limit theorem say in probability theory?"
The Bullet Screen sped up.
[This is the cornerstone of probability theory, very important. Watch this...]
Lin An repeated the answer.
The professor nodded, then asked,
"What's the Black–Scholes formula in financial mathematics?"
The Bullet Screen went quiet for a second, then started flooding with answers.
[The Black–Scholes formula...]
Lin An watched the Bullet Screen and repeated the answers word for word.
He spoke slowly because the comments were coming too fast. He had to read and memorize them as he went.
But he got them exactly right. Every symbol, every variable, every formula—all perfectly accurate.
After listening, the professor fell silent.
He stared at Lin An for a full ten seconds, then leaned back in his chair and folded his arms across his chest. He took a deep breath and slowly let it out.
"Have you studied all this before?"
"I don't remember."
"Then how do you know it?"
"I don't know."
Lin An said,
"But I know that I know it."
The professor suddenly felt a pang of regret. What a promising student... Why did he have to be crazy?
What a waste.
The professor sighed.
"Lin An, all your answers were correct."
He paused.
"Your fundamentals are solid. At least... at least as strong as those of the first-year doctoral students I supervise."
Darnell chimed in,
"So, Professor, can you help him get legal status?"
The professor glanced at Darnell, then at Lin An.
"I can try, but it'll take time. And I'll need your fingerprints so I can check the databases and see whether you have a record.
"You might have applied for a visa before. Maybe your fingerprints are in some system. We might be able to find your identity information."
Lin An nodded.
"Sure."
"One more thing."
The professor paused.
"You need a name—not Lin An, but a legal name you can put on official documents. Your real name, or... a completely new one."
"Just use Lin An."
"Lin An is a Chinese name. The pinyin is Lin An?"
"Yes."
"So your surname is Lin and your given name is An?"
"Yes."
The professor nodded, took a small notebook and a pen from his pocket, and wrote down the name.
Darnell leaned back in his chair, arms crossed, watching the professor write. Then he turned to Lin An.
"Bro, all that stuff you just mentioned—calculus, eigenvectors, Black-Scholes—you really know it?"
"Didn't I just answer your questions?"
"I mean, do you really understand that stuff, or did you just memorize it?"
Lin An thought for a moment.
"I'm not sure."
"You're not sure?"
"Right. I'm not sure whether I understand it or just remember it. But I think I understand it."
Darnell fell silent for two seconds, then shook his head.
"Bro, you're such a strange person. You don't even know who you are, but you know calculus. You don't even know if you went to college, but you know stuff taught to doctoral students. You don't even know if you have a passport, but you know how to kill people."
"Does it matter?"
"Bro, if that doesn't matter, then what does?"
"Happiness matters most."
The professor listened to their conversation without saying a word.
He lowered his head and looked at the name he'd written in his notebook... Lin An.
Then he added a note beside it: High intelligence, high-functioning, memory loss, possibly serious psychological issues. Recommend psychological evaluation.
But he didn't say any of that aloud.
Because he knew this young man wouldn't agree to an evaluation.
And besides, he didn't dare bring it up.
The professor closed his notebook, put it back in his pocket, and looked up at Lin An.
"Lin An, I'll help you, but you have to help me, too."
"With what?"
"About what happened tonight, I need you to promise that nobody will find out."
Lin An smiled.
"Professor, nothing happened tonight... Want me to find out who did it?"
Lin An waved the phone in his hand. He'd taken it from the body, but hadn't looked at it yet.
The professor stared into Lin An's eyes for three seconds, then nodded.
"All right."
He stood up, took off his coat, and handed it to Lin An.
"Here's your coat."
"Keep it on. It's cold outside."
"No need. I'll take a cab. It's just a few steps from the door to the car."
Lin An didn't insist. He took the windbreaker and put it on.
Darnell stuffed the last few fries into his mouth, stood up, and brushed the crumbs off himself.
"Bro, how are we getting back?"
"By bike."
"Are you sure? It takes over an hour to ride from here to Jamaica."
"Didn't you say you were in good shape?"
"I said I could ride fast, not that I wanted to ride for a long time."
"Then think of it as exercise."
Darnell took a deep breath, then slowly let it out.
"Bro, knowing you is the biggest... challenge of my life."
He'd meant to say "disaster," but at the last moment, he changed it to "challenge."
He felt that calling it a "disaster" in front of Lin An wouldn't be appropriate.
The three of them walked out of the fast-food restaurant.
In the small hours of the morning, Manhattan's air was as cold as a knife, cutting painfully into their faces.
The streetlights overhead flickered. In the distance, the city lights stained the skyline orange-red, and not a star was visible.
Darnell straddled the Roadster Bicycle, gripped the handlebars with both hands, and set his feet on the pedals.
Lin An sat on the back, one hand resting on Darnell's shoulder.
The professor stood outside the restaurant, watching them.
"Lin An."
He called out.
Lin An turned around.
"Tomorrow afternoon at three. Come to my office in the Mathematics Building, fourth floor, Room 412."
"All right."
Darnell pushed down on the pedals.
The Roadster Bicycle shot forward, its tires whispering against the asphalt.
The professor stood outside the restaurant, watching the bicycle ride farther and farther away until it disappeared around the corner of 110th Street.
Standing in the cold wind, he thought of something Lin An had said... "I'm the messenger God sent to save you."
The professor shook his head and gave a bitter smile.
God wouldn't send a murderer to save him.
Unless...
God was a lunatic himself.
The professor turned and went back into the restaurant. He sat down at the counter and ordered a hot coffee.
He needed to think carefully about how to deal with this lunatic tomorrow.
Before you continue