Summer twilight was looming over the old, cobbled streets of the town. The light coming in through the translucent leaves was punctuated by the shadow of thirteen-year-old Kacper, who rushed bent over a narrow passage, clutching a strange, glittering key in his hand. He stopped by the wall of the old brewery, where Lena was already waiting for him. Her eyes glittered impatiently - they both knew that this evening would not be ordinary. Behind their backs something meowed. They turned abruptly. Five cats were sitting on the wall: from a black one with a white patch on its muzzle, to a red one with a frayed tail. One of them, a huge tomcat with a grey pelt, spoke in a voice that resounded clearly in the silence: - Are you ready for the test, young people? Only you can solve the cipher that we have guarded for generations. If you fail, our whole community.... - here the cat suspended its voice and its moustache trembled - ...will disappear forever. Kacper looked at Lena, feeling both fear and a strange excitement. In front of them, a pale pattern appeared on his ankle, as if the reflection of a strange map. Lena reached out, tapped the first mark with her finger, and then dozens of glowing blinds emerged from the darkness. Then a hitherto invisible gap in the wall opened up, beyond which a feline community awaited - a city like they had never seen before. But before they could step inside, a piercing scream cut through the sky. The cats ran their backs together, and Lena and Kacper held their breath as a huge, dark silhouette suddenly emerged from around the corner....