From the beginning of the summer holidays, it seemed to Lena that her hometown was dormant and predictable. After exams and a whole school year, she had hoped for some adventures, but everything around her stubbornly persisted in its summer stillness. The lazy river, the familiar paths in the woods, even conversations with Oskar - her best friend - looked the same every day. On Thursday morning, Lena was pushing her bike through the sun-warmed streets when Oskar called her with an excited voice: - I've got something that will change our day! - he just said, then hung up mysteriously. They met by the old mill - a place about which various more or less plausible stories circulated. Oskar was already waiting for her, holding a heavily tattered leather-bound book under his arm. - Where did you get it? - Lena asked in disbelief, touching the bulging spine. - I found it in my great-grandfather's library. It was hidden behind a false wall. Check it out! - Oskar opened the book in the middle. The letters were arranged in strange, shiny patterns. Lena felt shivers run down her spine. The pages pulsed with light to the rhythm of her breathing. When they both simultaneously touched their fingers to the illustration depicting two moons in a dark blue sky, they felt a tug - as if someone was pulling them deeper into the page at once. The whole world swirled around them. The familiar trees, the river and the old mill ceased to exist. They opened their eyes to a forest of silvery leaves, and two huge moons shone above their heads - one blue, the other coppery. There was a strange smell in the air, something between fire and ice. - This... isn't Poland, is it? - Lena asked in a whisper, looking around in disbelief. - Rather not. - Oskar tried to look calm, but his eyes were wide with surprise. Suddenly, they heard a swish and saw a creature leaping out of the bushes, resembling a fox but with wings of fine blue feathers. It looked at them for a moment with sharp golden eyes, then disappeared into the thicket. Lena and Oskar slowly rose from the ground, trying to collect their thoughts. - Do you think the Book will let us go back? - Lena asked, flicking through page after page. Words suddenly began to disappear from the pages, as if someone was rubbing them off with an eraser. Then the sky flashed blood red, and a third, dark purple moon slowly began to rise above the horizon. When it appeared in its entirety, somewhere in the distance, there was a prolonged roar, from which the air thickened and the shadows around them began to lengthen. Lena and Oskar looked at each other frightened, feeling that now they were really no longer alone in this strange world. What was supposed to be the start of an ordinary holiday had become the start of something much bigger....