One March morning, as the rain drummed against the windowpanes like impatient students in a maths lesson, Karol slowly crossed the threshold of his school's old brick building. Ignatius Cipher High School may have looked typical, but Charles was well aware that it was rarely boring within its walls. The corridor was as chaotic as ever - chatty groups, laughter, shuffling shoes. Karol glanced past familiar faces: Nadia, who was still jotting something down in her notebook; Amadeus, the master of sarcasm and the school's IT specialist; and Lena, who was always up to something, especially if it required going beyond the school rules. A quarter of an hour later, they all met in Room 16, where they ran their favourite Cryptographers' Club. Apart from them, a few other people belonged to the club, but it was the four of them who set the tone for every meeting. Today, however, even Amadeus noticed something unusual: on the blackboard, just below the drawing of the old Enigma, someone had left a message written in strange characters. - 'I don't suppose this is your work, Charles? - chuckled Nadia, wrinkling her eyebrows. - 'No, it's the first time I've seen it,' replied a surprised Karol. They sat in a circle, passing a piece of paper to each other. Instead of the familiar letters, there were rows of symbols resembling some strange emoticons, some ancient alphabets, and some.... well, precisely, no one could decide what it most resembled. - Do you think this is a freshman prank? - wondered Amadeus, running his eyes over the lines. - 'We'd deal with the freshmen pretty quickly. 'But it looks too professional,' stated Lena, the bright green polish on her nails glinting as she turned the page. For the next few minutes they tried to work out the pattern, but to no avail. Finally, Nadia raised her head from above the notebook and said: - Let's see if there are any more signs like this somewhere. Maybe they are part of a bigger puzzle. They decided to split into pairs and search the school. Charles and Nadia set off towards the old library, which most students avoided by a wide margin. The corridors echoed with their footsteps. Amadeus and Lena headed for the basement, where used maps and old globes were stored. Charles' heart began to beat faster as soon as they crossed the threshold of the library. The shelves bowed under the weight of the bulky volumes, and the light coming through the stained glass windows painted fantastic patterns on the walls. A notebook lay on one of the tables, as if someone had just left it there in a hurry. Charles reached for it, and as he turned the page, another row of mysterious signs appeared to his eyes. - They are everywhere... - whispered Nadia. At that moment the lights went out in the room. A shadow moved across the bookcase. Someone was here with them. Charles blinked nervously, trying to see anything. They didn't know yet whether they should run away or stay and see what would happen next. Anything could happen now - and this was only the beginning.