On Monday morning, while everyone was still asleep at breakfast, Kacper had already been up for a long time. There were five different hats in his room: one with a huge brim, one with feathers, one ridiculously crooked, a fourth - shiny with glitter and a fifth - after his grandfather, a little too big and smelling a little too much of naphthalene. That day, Kacper had a plan. A big plan! He would finally invite Gabrysia and Maks to the Hat Club he had invented himself. A club that was going to revolutionise school life in 5B. But to make things more interesting, everyone had to wear a different hat and.... invent tasks for the rest. As the bell rang in the school corridors, Kacper carefully slipped into the cloakroom. Gabrysia was already there, putting her favourite pom-pom hat on her head. Maks walked right behind him, pulling something strange under his arm, wrapped in a scarf. - 'A secret club meets in a secret place,' whispered Maks with the look of a detective. - 'It's just a changing room, Poppy,' snorted Gabrysia. - But today it could become an arena of amazing adventures! All three burst out laughing, muffled by their winter jackets. Kacper took out an old cardboard box from under the bench. Inside lay several colourful, funny hats and a piece of paper with the words: "Challenge 1: Find something unusual in the school cloakroom!". - Oh no, there's nothing here.... Except for lost gloves and shoes," Gabrysia commented. But then Maks grabbed the door handle of one of the teachers' lockers, which someone had apparently forgotten to close. Inside lay a mysterious metal tin, all covered in stickers with flamingos and the word "SNACKZ". - 'Oi, this probably shouldn't be in here,' whispered Maks with concern. Kacper, unable to resist, opened the tin. There were no crisps inside, just.... some feathers and a crumpled piece of paper with a strange drawing on it. It showed a diagonal line, like a section of a map, and a message scrawled in black font: "For hooded only!". At the same moment, something fluttered in the corner of the cloakroom. Gabrysia jumped up and Maks rushed behind the bench. On the bench next to the cardboard box something began to move.... The three friends held their breath, staring at the shadow moving closer and closer to the hats....