Mira was sitting on the roof of the school, with her rucksack under her knees. Next to her, Tymek was kneeling and holding a torch over the cables. They had a small antenna, made from an old canopy and wire. Mira's tablet showed jumping dashes, like waves on a lake. Above them, a late sickle of the moon hung overhead and a few planes winked. White markings could be seen on the concrete: A1, A2, B6, C3. - 'If we catch a satellite, I'll give you my bar,' she whispered. - 'I prefer knowledge,' replied Tymek, although a candy bar sounded good too. Suddenly the graph froze and short, even peaks appeared. Mira switched on the simple decoder and listened to the tapping. It wasn't an SOS or random noise from the city. The letters appeared on the screen one by one. A message flashed across the screen: Do you read me, Mira? Entrance B6. Open slowly. Mira and Tymek looked at the white letters painted with paint. B6 lay a metre away from them, by the old ventilation chimney. The board was warm, like a radiator, and vibrated gently. - 'Don't touch it,' said Tymek, but he was already tilting the torch. A pale light shone in the crack and she smelled ozone. Someone, or something, moved the mechanism under the school roof. The lock clicked, the concrete flap vibrated and began to lift. It was dark inside, but the bottom shimmered a cold blue. From the depths came a steady murmur, as if from a hidden engine. The tablet itself changed screen and displayed a new message. A message flashed on the screen: Permissions: Mira. Passage test. Step one. - 'I think this is a joke,' whispered Tymek, louder than he had planned. A chill rose from below, and the light blinked three times. Something metal squeaked, as if a lift was going up. Mira tightened her fingers on the torch and leaned over the opening. Just at their feet, a thin moving line lit up. The line moved forwards and quietly honked. - It's counting on us,' Mira whispered as the flap swung wider. Something round slid out of the darkness and stopped just below them.