She was extremely careful about her diet, never giving anyone a chance to tamper with it. She observed the way each classmate looked at her, trying to discern the degree of malice in their eyes. Inevitably, Susan Wright began to suffer from insomnia, finding it hard to fall asleep and often waking up suddenly for no reason.

Susan Wright lay awake in the darkness, listening to the rise and fall of breathing in the room. The others must have been asleep for a long time. Another sudden bout of heart palpitations struck her. This can’t go on, she thought, I have to come up with a solution. There was a venomous snake hiding in her shadow, but every time she turned around, she couldn’t see it.

She had to see it. When it came to bite her, surely she would see it then?

If she could actively create an opportunity, luring that person to strike again, then she could discover who it was.

If I were that person, Susan Wright thought, if I were the murderer.

Slowly, without even realizing it herself, a faint smile appeared on her face in the darkness. Yes, this was a realm she was familiar with.

Susan Wright didn’t sleep at all that night, and by dawn, she decided to stay in the hospital for a while.

She had been planning this hospitalization for some time, pondering over many details, so it wasn’t until November 11th that it finally happened. On the surface, it looked like a complete accident: she participated in a drug trial that was supposed to be very safe. The drug was a cephalosporin antibiotic that had been approved by the FDA in the United States and had been on the market for years, but it was entirely new in China. During the second intravenous injection, Susan Wright showed obvious discomfort and began vomiting. She was admitted to the hospital for several days of tests, but nothing was found, so it was chalked up to a drug allergy—a common occurrence.

During her stay, aside from her father and the teacher in charge of the drug trial, only Fiona Bennett came to visit her, which was a bit lonely. But this was within Susan Wright’s expectations. Not having too many visitors was actually good; she insisted that the doctor add a bunch of unconventional tests for her. She didn’t want her classmates or her father to know about these strange tests. For example, she had a full set of blood tests for parasite eggs.

Some of her symptoms reminded Susan Wright of her older sister. Rationally, she knew it was impossible for anyone to know how her sister had died, or for anyone to harm her in the same way. But reason and emotion always go their separate ways.

The test results brought Susan Wright some relief—no parasite eggs. But there were also no other signs of poisoning.

On the way back to school, Susan Wright wondered if she was just being too paranoid. She began to feel anxious about the situation with the box; before going to the hospital, she had hoped to see some change in the box, as it was a carefully designed trap. But now, she hoped nothing had changed inside.

It was a beautiful camphorwood box, fastened with a brass lock, kept in her corner. When Susan Wright opened the box, she didn’t avoid her roommates—this was where she kept her important personal items, and it was perfectly normal to open it at any time. The box was packed full; on the top layer were "Letters from Father Fu Lei," a xiao (Chinese flute), a sewing kit, and other items, all neatly arranged, just as always. Susan Wright squatted in front of the box, her expression hidden from everyone.

A moment ago, she had been relieved by the hospital test results, hoping it was all a false alarm. Now, it felt as if a centipede was crawling on the back of her head.

Before going to the hospital, the letter she had placed in the box was gone.

It was a letter addressed to the poisoner.

Susan Wright struggled to her feet, trying hard to act as if nothing had happened, climbed back onto her bed, and drew the bed curtains. Then, she pulled two thin sheets of paper from her bag and unfolded them.

They were copies of the letter, made with blue carbon paper.

You must be very surprised—I am too. I’m glad to be able to correspond with you. It took a lot of courage for me to do this, so please don’t have any unnecessary concerns. When I realized your existence, I was especially happy; I suppose we’re kindred spirits, even though what we’re doing is dangerous and illegal. But no matter what, she deserves retribution—otherwise, it’s just too unfair!

This is how I introduce myself. Susan Wright is currently in the hospital. You must think this was an accident, since you didn’t make a move this time. Now I’m telling you, this was no accident—it was orchestrated by me. Of course, this is just a lesson; I don’t expect to do anything to her. She always manages to be saved and return to us, and it won’t even take long. But this is just the beginning. I’ve joined in, and there’s a long road ahead. I plan to take it slow, just like you. As for my real identity, I don’t think you’ll try to find out, just as I won’t recklessly ask your name. After all, we see each other every day, greet each other, and are all members of this training class.

You must be very curious how I discovered you.

Actually, there’s no direct evidence, so you don’t need to worry. At first, I noticed that Susan Wright’s health was deteriorating, which showed in many subtle ways. I believe any classmate could have noticed it. But most people wouldn’t think much of it—after all, everyone’s health fluctuates, maybe she’s just in a slump or got sick naturally. That’s what I thought at first, but Susan Wright’s increasing neurosis made me suspect something else. She seemed to think someone was out to get her, and became more and more cautious. So I wondered, could there be someone else with the same idea as me, who had already taken action? After the incident with the honey jar, I was convinced—you must exist!

I won’t hide my intentions: a woman like Susan Wright doesn’t deserve to go on living in this world! But I haven’t figured out how to achieve this yet. Of course, I don’t plan to use any violent means, and it can’t be traced back to me. Ideally, she would just quietly pass on to another world, and I would become a respected doctor. But this method can only be used once, and it’s not enough to kill her. What should I do next? I really want to know what you plan to do, and how you go about it. It must be brilliant—able to ruin her health without being detected in the hospital.

I look forward to your reply. However, we need a safe mailbox. How about the pine grove? Facing the basketball court, the second bench from the east, on the back of it, count the sixth pine tree to the north—the one with the odd shape and a small hole in the trunk. You can leave your letter there.

May Susan Wright rest in peace soon.

A classmate

Every word and sentence of this letter had been carefully considered by Susan Wright. Sometimes she put herself in the shoes of the fictional murderer, sometimes she stepped back to check if the tone was appropriate. In short, she had to make the real murderer willing to reply. That way, she would have infiltrated the enemy, becoming one of them.

She had placed the letter on the very top layer of the box. Susan Wright imagined what she would do if she were the poisoner. She had always been good at putting herself in others’ shoes; seeing the world from another perspective was her way of life. Yes, she would definitely want to see what was in Susan Wright’s private box, to learn as much as possible about her secrets. If there was food in the box, it would be the perfect opportunity to poison it. When Susan Wright was suddenly sent to the hospital and didn’t have time to lock the box, would the poisoner miss this chance? To get the letter out, Susan Wright had orchestrated this whole act herself. Now, the letter had really been taken. So, there really was a poisoner—this was absolutely certain, beyond any doubt.

Now, all she had to do was wait for a reply.

3

It was already the fourth day since she’d returned to school.

Every day, she went to check the tree hole. The first few times, coming up empty made her anxious; she kept wanting to check again, but had to restrain herself—going too often would be suspicious.

With her hands behind her back, Susan Wright strolled around, pretending to take a walk, winding her way to the tree hole. After making sure no one was around, she quickly reached in.

Her heart suddenly pounded wildly. When she pulled her hand out of the tree hole, there was a white envelope in it. Susan Wright folded the envelope and stuffed it into her pocket. Unable to wait until she got back to her dorm, she ran to the nearest bathroom in the teaching building, locked herself in a stall, and took out the envelope.

It was the kind sold at the school’s convenience store, with the school’s letterhead, just like the one she had used for her first letter—plain and untraceable.

Her hands were even trembling a little as she unfolded the letter.

You don’t need to know my methods. Your approach this time was stupid and pointless. Don’t get yourself caught and drag me down with you. A medical student who can’t come up with a better plan? With skills this poor, you’ll be the next one to get weeded out!

Susan Wright doesn’t have much time left. It makes no difference whether you’re involved or not.

Another classmate

Susan Wright clenched the letter in her fist. At this moment, she didn’t feel anger or fear, but excitement.

They’d taken the bait!