"At that time, I actually had a bit of a crush on Winnie Hayes, though it was still far from love. I told her I wouldn't call the police. If you trust me, I’ll help you figure something out. I also really hated Susan Wright, but honestly, there was no need to get ourselves involved to that extent. I was very familiar with the toxicology lab and knew exactly what substances could be found there. That night, in the toxicology lab, Winnie Hayes and I chose thallium as the poison. I also tried to persuade her that there was no need to actually kill Susan Wright, but she had to be taught a lesson—what William Williams suffered had to be repaid to her. Next came the question of how to administer the poison. If we didn’t want to get ourselves caught, choosing the right poison was important, but the method was even more crucial. First, there had to be a process. If a large dose of thallium was given all at once, it would cause a violent reaction in a short time and be discovered immediately. To be safe, it had to be administered in small doses over multiple times. But the more times it was done, the harder it would be for just Winnie Hayes and me to keep everything seamless. I asked Winnie Hayes if she was willing to take a gamble. At that time, everyone in the training class hated Susan Wright, just to varying degrees. If we could get more people on board, things would be much easier. So, on one night in the second week after the semester started, we notified everyone and found an empty classroom for a meeting. Oh, of course, you and Susan Wright weren’t among them."

That sweltering summer night was something Matthew Mitchell could never forget—not just him, but also Winnie Hayes, Frank Bishop, and everyone in the training class. Because their lives, their fates, their place in the world and in their own hearts, were changed forever. Of course, this also included those who weren’t present, like Susan Wright, Fiona Bennett, and Gabriel Adams.

Most people couldn’t clearly realize this at the time. Around 8:30, everyone had arrived. Winnie Hayes locked the door, and Matthew Mitchell went to close every window. The atmosphere immediately grew heavy. When the two of them invited everyone to the meeting, they hadn’t said what it was about, but everyone agreed to come, and no one pressed for details.

Only half the lights in the classroom were on. There was no air conditioning, no fan. Just from sitting down and closing the doors and windows, many people’s sweat made their hair stick tightly to their scalps and cheeks. The stifling heat pressed in from outside and pushed up from within, leaving nowhere to escape.

Winnie Hayes spoke first. She talked about William Williams’s suffering, about Susan Wright’s despicableness, about what she wanted to do, and about how she was caught by Matthew Mitchell in the toxicology lab. Her words were inarticulate and her logic was confused, but it was enough for everyone to feel her mood and determination.

“That night, as soon as I entered the classroom, I had a feeling that everyone knew why they were there.” Unconsciously, Matthew Mitchell had already put down his crossed leg, his fingers interlaced and resting on his knees, his whole demeanor growing tense, as if he had returned to that closed classroom.

“When Winnie Hayes said she wanted to kill Susan Wright, I thought there would be an uproar, or at least some commotion, but there wasn’t. No one showed any expression, made any movement, or uttered a sound. At that moment, I felt settled. I knew—this is the heart of all people. I told everyone that the reason I stopped Winnie Hayes wasn’t just because I couldn’t let her become a murderer, but because this wasn’t just her problem—it was the problem of our entire training class. William Williams, who should have belonged to our class, was gone, but Susan Wright remained. We came here to study medicine to save lives, not to take them, but Susan Wright was not qualified to be a doctor who saves people. She had to pay a price, or else the world would be too unjust. I hoped we could reach a consensus: Susan Wright had to be weeded out, even if it meant using some unspeakable means, even if Susan Wright would be hurt, just as she had hurt William Williams. After I finished, I unlocked the door and said, if any of you disagree, want to leave, report to the school, or even call the police, it’s fine—you can go now. But Winnie Hayes and I will stay here.”

Matthew Mitchell paused here, looked at Fiona Bennett, and smiled.

“You can guess the result, can’t you? Two minutes later, I locked the door again. From then on, we formed an alliance—a collective alliance to poison Susan Wright.”

“That’s terrifying,” Fiona Bennett said softly. When everyone could be the one to poison, and everyone could cover for each other, it became almost impossible to guard against. She still remembered how she and Susan Wright had analyzed possible poisoning scenarios, and the first thing they ruled out was ‘in full view of everyone.’

“Is it hard to understand? Actually, not really.” Matthew Mitchell shook his hand. By now, he had pulled himself out of the memory and was relaxed again.

“You have to understand, at that time, no one really wanted to kill Susan Wright. I was responsible for providing the thallium to everyone, and each person took a little. But in reality, not everyone actually administered the poison. Some people never did anything—they just kept silent.”

“Not taking action is still being an accomplice!” Fiona Bennett said.

Matthew Mitchell shrugged. “I agree. But, with everyone acting this way, would you really find it so strange? What was it that made the best class in the medical school, a group of young people with above-average moral standards, make such a choice? Ask yourself honestly: if you had already been a member of the training class, if you weren’t good friends with Susan Wright, if you had been in that classroom at the time, would you have left?”

Fiona Bennett didn’t answer. She didn’t know the answer. Or maybe she did—knowing her own cowardice, she probably wouldn’t have had the courage to stand up and walk out alone. Thinking of this, she realized that Matthew Mitchell hadn’t really given anyone a chance to leave. There were silent ones in the training class—not everyone actually poisoned her. Silence meant hesitation, meant struggle. On one hand, they couldn’t let themselves become perpetrators; on the other, they couldn’t betray their classmates for someone like Susan Wright, whom they deeply hated. If Matthew Mitchell had given everyone a day to think it over, or even phrased it as ‘those who agree leave, those who don’t stay,’ things might have been different.

“So, can you tell me now who actually poisoned her and who didn’t?” Fiona Bennett asked.

Matthew Mitchell shook his head.

“With your situation now, I thought you wouldn’t keep any more secrets!”

“Of course, at this point, I have no reason to hide anything from you.” Matthew Mitchell smiled at Fiona Bennett. Fiona Bennett’s heart sank. She had been probing a little just now, but now she saw there was no hope.

“What I mean is, even I don’t know who poisoned her and who didn’t. We had a place—whoever managed to poison her that day would make a mark there. We agreed on the dosage each time, very small. If there were a lot of marks in a day or a few days, the others wouldn’t poison her again, to avoid an overdose that could be fatal. As for what kind of mark to make, we never specified—people could carve whatever they wanted, and it was possible for one person to use a different mark each time. So, you could only know how many times Susan Wright was poisoned that day, but never who did it.”

“Carve a mark? Where did you carve the marks?”

“You’ve seen it—that desk.” Matthew Mitchell smiled faintly.

“The desk covered in marks? The one with the symbols for gold, wood, water, fire, earth, moon, and sun?”

Matthew Mitchell nodded. “It’s really impressive that you managed to figure out the pattern.”

Fiona Bennett finally understood why, apart from the seven time symbols, she could never find a pattern in the others—there simply wasn’t one!

But that desk, which recorded how many times Susan Wright was poisoned each day, was later used as a mailbox! Thinking of how Susan Wright, for a long time, carefully placed letters carrying all her hope for survival into the mailbox, while ignoring the dense marks on it, Fiona Bennett felt a chill in her heart.

Such cruelty was too much.

Fiona Bennett did her best to restrain her anger, not wanting to give Matthew Mitchell a chance to gloat. She also knew Matthew Mitchell wouldn’t give her much time—before she fully recovered her strength, he would definitely make his move.

“Since you never intended to kill her at first, then how did Susan Wright end up dying?”

“Those who bring misfortune upon themselves cannot escape it.” Matthew Mitchell said this as if he were on the side of justice.