If someone had once told Nina that a Tuesday afternoon in a dingy IT room would open the door to adventure for her, she probably would have laughed. But it was there, along with Adam and Maja, that she found an old, dusty key in Mr Thomas's desk drawer. An ordinary key, but with an engraved, barely visible owl symbol and the number 12. Adam was the first to reach for the key. "It's probably from some locker in the library," he chuckled with his usual confidence. However, Nina remembered the legend of the clock in the school tower - it was rumoured to be hiding something that only the town's founders knew about. The last repair work on the tower had ended strangely abruptly, and no one had gone up there since. Mutual glances and without words they made a decision: they had to climb the tower. The next day, just after the last lesson, they snuck up to the third floor, where the spiral staircase leading to the tower began. Every step echoed. When they finally reached the heavy iron door, Maja pulled out the key. As they watched Nina put it into the lock with a shaking hand, they all held their breath. The door opened with a quiet rasp. Inside the tower smelled of dust and something else - something alien. A huge clock stood in the middle and a wooden box beside it. Adam approached first. The same owl symbol was carved on the age-old boards of the chest. Next to it, in the dusty light, flashed a metal plaque with the inscription: "Face the past and the future will be open to you". Before Nina had time to warn her friends, Adam lifted the lid of the box. Inside lay something that looked like an old diary, a few rusty keys and a a small but very modern phone charger. Suddenly the clock started ticking louder, the hands moved of their own accord, and a beam of strange blue light came through the window. The three friends looked at each other, feeling that they had just crossed an invisible boundary beyond which nothing would be the same again....