He wondered if his classmates knew everything. Maybe even his teachers knew. He felt their furtive glances weaving together above his head like a fishing net.

He opened his history book at random and started learning by heart the whole sequence of dates that appeared from that page onward. The list of numbers, lined up without any logical meaning, formed an ever longer trail in his head. As he followed it, Mattia slowly moved away from the thought of Denis standing in the shadow and forgot the void that now sat in his place.

During break time Alice slipped into the infirmary on the second floor, a narrow white room furnished only with a hospital bed and a mirrored cabinet with the essentials for first aid. She had ended up there only once before, when she had fainted during PE because in the previous forty hours she had eaten only two whole-grain crackers and a low-calorie snack. That day the gym teacher, in his green Diadora tracksuit, his whistle, which he never used, around his neck, had said to her think carefully about what you're doing, think very carefully. Then he had gone out, leaving her alone under the fluorescent light, without anything to do or look at for the whole next hour.

Alice found the first-aid cabinet open. She took a wad of cotton wool the size of a plum and the bottle of rubbing alcohol. She closed the door and looked around for a heavy object. There was only the wastepaper basket, made of hard plastic, a dull color halfway between red and brown. She prayed that no one would hear the noise from outside and shattered the mirror of the little cupboard with the bottom of the basket.

Then, being careful not to cut herself, she picked up a big triangular splinter of glass. She caught the reflection of her own right eye and felt proud that she hadn't cried, not even a bit. She stuffed everything into the center pocket of the baggy sweatshirt she was wearing and went back to class.

She spent the rest of the morning in a state of torpor. She never even glanced at Viola and the others and didn't listen to a single word of the lesson on the theater of Aeschylus.

As she was leaving the class, behind all her classmates, Giulia Mirandi furtively took her hand.

"I'm sorry," she whispered into her ear. Then she kissed her on the cheek and ran after the others, who were already in the hallway.

Alice waited for Mattia in the atrium, at the bottom of the linoleum-covered staircase down which poured a chaotic stream of pupils headed for the exit. She rested a hand on the banister. The cold metal gave her a sense of tranquillity.

Mattia came down the stairs enveloped by that foot and a half of emptiness that no one other than Denis dared occupy. His black hair fell over his forehead in tousled curls. He watched carefully where he placed his feet, leaning slightly backward as he descended. Alice called out to him, but he didn't turn around. She called again, more loudly now, and he looked up, said an embarrassed hi, and made as if to head toward the glass doors.

Alice elbowed her way through the other students and joined him. She took him by the arm and he gave a start.

"You have to come with me," she said.

"Where?"

"You have to help me do something."

Mattia looked around nervously, in search of some kind of threat.

"My father's waiting for me outside," he said.

"Your father will wait. You have to help me. Now," said Alice.

Mattia snorted. Then he said okay but he couldn't have said why.

"Come."

Alice took him by the hand, as she had at Viola's party, but this time Mattia's fingers spontaneously closed around hers.

They left the crowd of students. Alice walked quickly, as if she were escaping from someone. They slipped into the deserted corridor on the second floor. The doors leading to the empty classrooms conveyed a sense of abandonment.

They went into the girls' bathroom. Mattia hesitated. He was about to say I'm not supposed to be here, but then he let her drag him in. When Alice took him inside a cubicle and locked the door they were so close that his legs started trembling. The space not taken up by the old-style hole-in-the-ground toilet was nothing more than a thin strip of tiles and there was barely room for their four feet. There were pieces of toilet paper scattered on the ground half-stuck to the floor.

Now she's going to kiss me, he thought. And all you have to do is kiss her back. It'll be easy; everyone knows how.

Alice unzipped her shiny jacket and started to undress, just as she had at Viola's house. She untucked her T-shirt and lowered the same pair of jeans halfway down her bottom. She didn't look at Mattia; it was as if she were there on her own.

In place of Saturday evening's white gauze she had a flower tattooed on her skin. Mattia was about to say something, but then fell silent and looked away. Something stirred between his legs and he tried to distract himself. He read some of the graffiti on the wall, without grasping its meaning. He noticed how none of the writing was parallel to the line of tiles. Almost all of it was at the same angle to the edge of the floor and Mattia worked out that it was somewhere between 30 and 45 degrees.

"Take this," said Alice.

She handed him a piece of glass, reflective on one side and black on the other, and as sharp as a dagger. Mattia didn't understand. She lifted his chin, just as she had imagined doing the first time they had met.

"You've got to get rid of it. I can't do it on my own," she said to him.

Mattia looked at the glass shard and then at Alice's right hand, which pointed at the tattoo on her belly.

She anticipated his protest.

"I know you know how to do it," she said. "I never want to see it again. Please, do it for me."

Mattia rolled the shard in his hand and a shiver ran down his arm.

"But-" he said.

"Do it for me," Alice interrupted him, putting a hand to his lips to shut him up and then removing it immediately.

Do it for me, thought Mattia. Those four words stuck in his ear and made him kneel in front of Alice.

His heels touched the wall behind him. He didn't know how to position himself. Uncertain, he touched the skin next to the tattoo, to stretch it better. His face had never been so close to a girl's body. The natural thing to do seemed to be to breathe in deeply, to discover its smell.

He brought the shard close to her flesh. His hand was steady as he made a little cut the size of a fingertip. Alice trembled and let out a cry.

Mattia recoiled and hid the piece of glass behind his back, as if to deny that it had been him.

"I can't do it," he said.

He looked up. Alice wept silently. Her eyes were closed, clenched in an expression of pain.

"But I don't want to see it anymore," she sobbed.

It was clear to him that she had lost her nerve, and he felt relieved. He stood up and wondered if it would be better to leave.

Alice wiped away the drop of blood trickling down her belly. She buttoned up her jeans, while Mattia tried to think of something reassuring to say.

"You'll get used to it. In the end you won't even notice it anymore," he said.

"How is that possible? It will always be there, right before my eyes."

"Exactly," said Mattia. "Which is precisely why you won't see it anymore."