Not much time had passed after the Assessors' visit when Aunt Sybil asked Sofia to come up into the tower. As Sofia climbed the steps that suddenly seemed very steep, she was filled with dread as if her bones had been replaced by lead.

Aunt Sybil was sitting at her usual place, looking out the window. A chair was placed in front of the table. It was a wordless request to sit down. A large leather-bound tome was lying on the table. It was closed with an unscathed red seal.

"Come in," Aunt Sybil said when Sofia hesitated. "Sit down."

Sofia did as she was told. She kept a physical distance from the table, from the book, from the window that she was supposed to be looking through for the rest of her life. She still had not told Orì that she was supposed to become Guardian of the Bridge. It would mean that their friendship was in direct violation of what she would have to swear to uphold.

"You have made a good impression on the Assessors," Aunt Sybil said. "They were quite taken with your seriousness and attention to detail. And with your honesty." Nothing in Aunt Sybil's expression alluded to the dishonesty of Sofia's testimony, as if she had forgotten what had really occurred. She had accepted the Assessors' conclusion as her own. "They have approved you as the next Guardian of the Bridge. I am very glad. I am certain that you will not disappoint."

She gave Sofia an encouraging smile, and Sofia forced herself to return the smile. Inside, she felt like her heart was sinking into an abyss.

"You don't need to worry," Aunt Sybil said. "We will bestow as much time on your training as necessary. You won't be required to know and do everything right away, and I am well aware that this work takes a while to get used to, to build up the stamina. I wasn't as lucky as you, to have a teacher who cared about me." A hardness entered Aunt Sybil's face. "When I started my training, the Guardian was an old woman named Tessina -," she practically spat the name. "She was not very understanding. She wanted to give over her duties as quickly as possible, and after Sermon had proved himself an unsuitable candidate, she had little compassion for any weakness on my part. It was a tough time. But being the Guardian of the Bridge is a worthwhile and meaningful occupation, and I will make sure that you will get all of what I didn't get. Time, understanding and compassion. And a complete and thorough training, of course."

"Thank you, Aunt Sybil."

Aunt Sybil gestured towards the book. While she had been talking, Sofia had examined it more closely, not able to keep her natural curiosity completely at bay. There was an elaborate print on the cover, an abstract map depicting the two worlds with as few details as possible. The border ran precisely through the middle. The book was closed with a strap, fastened with a thick red wax seal. The stamp showed a bridge, not unlike the one outside the window, but while the bridge started out from a piece of land, it was cut off before reaching the other side, as if the world had come to its natural end, into nothingness.

"Open it," Aunt Sybil said.

Sofia tentatively put her hands on the book. It was heavy, and it smelled of stone and rain and as if it had been stored in a cellar.

"You need to break the red seal," Aunt Sybil explained. "It is your book and yours alone. You will be the only one to open it, read it, and care for it. You are allowed to enter notes, and at the end of your tenure, it will be handed over to the Assessors for safekeeping."

Sofia looked at Aunt Sybil's small ledger, bound in nondescript brown leather.

"Where is your book?"

"This is not it," Aunt Sybil said. "This is just for my daily notes, as a memory aid. Your Guardian Book contains all the instructions you need, the history of our two worlds and the guidelines for peaceful coexistence. You may write notes and suggestions, but you should always be respectful and humble. We follow a tradition that is centuries old and has been very well thought out. There is no need to put your personal stamp on it."

"What have you noted?" Sofia asked.

"Nothing," Aunt Sybil said with pride.

"But it will be as if you were never here."

"That is the way it should be."

"Aren't you -" Sofia hesitated. "Aren't you sad about that?"

Aunt Sybil smiled patiently.

"I might have been when I was your age. But as you get older, you learn that it is a good thing not to be seen. It ensures your safety."

Sofia didn't know what she meant. Safe from what? From whom? There weren't exactly sea monsters emerging from the waters. Nothing ever happened in Border Village Number Seventeen. Except -, except for Orì.

"Yes, Aunt Sybil," she said.

"Now, open your book."

Sofia examined it from every side to make sure the seal would open evenly. She tore the string carefully, and the seal broke with an ancient, dry and brittle sound. Little shreds of wax crumbled away like ash.

Sofia opened the heavy binder, half expecting dust to rise into her face and the book itself to dissolve under the heavy burden of time. But nothing happened. The pages were old and yellow, but perfectly clean. The writing was neat and legible, the tone bleak and sober, as if deliberately meant to bore the reader.

Sofia scanned over the first few lines and immediately started to lose interest.

"I know that it is not the most exciting reading," Aunt Sybil said. "But you will learn to appreciate it. It holds everything you could ever wish to know."

Sofia doubted this very much.

"Yes, Aunt Sybil," she said.

"You need to read it, to study it until you can quote it blindly. Before you are ready to become Guardian of the Bridge, I will test your knowledge of the book, and I will not let you pass until I am completely satisfied that you know every wor."

Sofia looked at the book. It seemed to swell in front of her.

"Yes, Aunt Sybil."

She seemed to have unlearned to answer in any different way, but Aunt Sybil didn't notice. She was pleased with the way the conversation was going.

"Guardian of the Bridge would be called a holy duty if we still talked in such silly spiritual notions. I am not even supposed to use words like this, but I want to emphasize to you the importance of the duty you are about to take onto yourself. There is little thanks for it, but you should know inside your heart that your sacrifice is worth it."

"My sacrifice?"

"Your time," Aunt Sybil said. "Your life."

Time and life were incomprehensible concepts at that moment.

There was a loud thumping at the front door, and Aunt Sybil's head shot around.

"Who could that be? At this time." Her voice expressed anger, inconvenience and worry at the same time.

She got up to go downstairs, and Sofia followed her.

Uncle Tomas had already opened the door, though his posture was unsteady, and his eyes were slightly glazed over.

"What is it?" Aunt Sybil said, pushing past him, taking charge.

Mr Borrealis was standing at the door. His round jolly face was pale, not looking jolly at all. His mustache was trembling, and his lips were even whiter than the rest of his face.

"Sybil -," he started. He saw Sofia behind her. "Oh, Sofia. Hello, my dear, how are you?"

"I'm fine, Mr Borrealis," Sofia answered, reflexively.

"That's good. That's very good. Have you seen Pip and Tin, today?"

"No."

Evidently, this wasn't the answer he had hoped for.

"What about yesterday?"

"No. It's been a few days, I think. I don't know exactly."

Mr Borrealis' eyes went upwards as if he was praying, or maybe fainting.

"What happened?" Aunt Sybil asked.

"They're gone!" he cried out. "They've vanished."

"Nonsense," Uncle Tomas muttered. "Children don't vanish. They're playing somewhere."

Mr Borrealis shook his head. He shook it so hard that his mustache came loose in strands.

"They were not there when my wife went to wake them up this morning. Their beds were untouched. And those boys wouldn't know how to make a bed to save their lives."

He looked at them in despair, his eyes fixed on Aunt Sybil as if she was supposed to solve this unsolvable problem.

Her lips were pressed into a thin line. She nodded slowly, as if aware that saying things out loud meant that they would become reality from that moment on.

"Pip and Tin are missing," she said in a grave voice.