In the block of flats at 13 Wariacka Street, everyone knew Basil - Philip and Berry's cat. He was no ordinary rooftop cat: once he fell asleep in the washing machine (fortunately not switched on!), another time he slept all night in a pot of basil (that's how he got his name, although Dad preferred to call him 'Potato'). On Sunday morning Basil had planned something again. Berry was the first to notice: the cat didn't drag himself lazily awake, but glanced at Philip and winked at him. Of course, Philip thought he had been predicted, because Basil is ruled solely by his lust for cat munchies and a bit of madness. Basil's plan started innocently enough: first he stole one sock from his parents. Then he silently rolled up all the pens from Philip's pencil case and stacked them in the corners. Jagoda noticed that the cat was sneaking erasers and carefully hiding them under the bed. To top it all off - to the absolute despair of the downstairs neighbour - Basil had organised a nighttime obstacle course of shoes scattered all over the corridor. After three days of chaos, the children began to wonder if their cat was leading a double life. In the evenings, he would stare out the window as if waiting for a signal from another world. That evening, when Dad closed the kitchen door and drew the blinds, Basil suddenly jumped onto the windowsill, hissed like an old modem and... a coloured LED blinked on his neck. Berry and Philip looked at each other with wide-open eyes. At that moment, there was a prolonged whistling sound under the block, and from the stairwell came something that sounded like the sound of a rocket taking off into orbit....