The summer evening was unusually warm, and the air smelt of warm grass. Lena, leaning against the saddle of her bike, looked at her friends Olek, Maja and David. They were all looking at each other with excitement and slight apprehension. Behind them, hidden among the dense trees, an old fort, abandoned for years, could be seen. ‘Are you sure we want to go in there?’ Olek asked, clutching a torch in his hand. ‘We have to! Yesterday I saw lights at the main entrance. Someone was there, although supposedly no one has visited the fort for ten years,’ said Maja, her eyes shining with emotion. David pushed aside a branch, revealing a partially overgrown path. ‘Stop hesitating. At most we’ll meet a… a cat or a bat.’ They moved slowly, wading through the tall grass. When they reached a massive gate, they noticed trampled ground, with footprints leading deep into the shadows. Lena pulled out her notebook, in which she wrote down everything she wanted to describe in a book one day. She noted: ‘New trail: fresh footprints.’ The fort inside was cool and smelt damp. The boys were drawn to the old crates. One of them was open, and inside were a yellowed letter and a strange metal key, as if for a very old lock. ‘Look!’ whispered Olek, pulling out the letter. On the paper was a map with a strange sign in the shape of an eye. Suddenly, there was a quiet creaking of the floor in the silence… Someone or something was in the fort with them. The group froze, staring into the darkness. A barely visible shadow appeared in the corridor. Was it another adventurer, a mysterious guardian of the fort, or perhaps someone with much darker intentions? Suddenly, the silence was broken by a loud clatter, and the light of their torches danced on the walls. Lena clutched the key in her hand, ready for whatever was about to happen…