The old house on the outskirts of town was a place full of undiscovered nooks and crannies for Michael. Ever since he and Julia had found a rusty key in the garden, they had returned every day after school to try to open more doors, cupboards and chests. The house looked as if someone had lived in it a long time ago and suddenly disappeared - there were abandoned hats on the chairs and tea stagnant in cups in the kitchen. But the biggest mystery was the attic, which was locked with three triggers. One Thursday, when the sun was hiding behind the giant sycamore trees, Michael turned the key he had found in the old-fashioned lock. The door creaked open and revealed a staircase leading upwards, shrouded in dust and shadows. With their hearts beating like a hammer, they cautiously made their way up, holding hands. The attic looked like the workshop of a mad inventor. Clocks stood everywhere: round clocks, square clocks, pendant clocks, pocket clocks and clocks that seemed to be made of things no one would expect to find in a timepiece. Manuscripts lay spread out in the middle of a large table, and sketches depicting strange devices entwined with wires and cogs hung on the walls. In the corner stood a huge clock with a pendulum that, instead of the usual metal, had a piece of shiny stone embedded in it. Julia discovered a tiny inscription on the dial: 'Professor Rutkowski'. - My great-grandfather,' whispered Michal in disbelief. Michal reached into a table drawer and pulled out a bundle of old notes, on which lines full of mathematical formulas, dates and disturbing words stretched: "offset", "zero point", "return". While Julia looked through the sketches, Michael carelessly pressed a button on the base of the clock. The silence was broken by a sound like distant thunder, the light in the room went out and images began to appear around them - at first blinking, then becoming clearer. They saw the street in front of the house from a hundred years ago, then the city of the future: full of aerial trains and hovering cars. Julia watched with wide-open eyes, while Michael felt the floor tremble under his feet. As he tried to switch off the machine, the dial of the clock began to turn faster and faster, and the hands went wild, showing impossible-to-read numbers. Then something - or someone - knocked on the loft door. The sound came loud and clear, although they seemed to be completely alone. Julia froze. Michal wondered whether to dare open the door, or perhaps hide behind Professor Rutkowski's table....