The warm, damp air of the evening enveloped the streets of the Old Harbour Town as Lena, Michael and Kacper shuffled through the side alleys, holding torches in their hands. Summer was in full swing and the seaside harbour, though full of bustling tourists during the day, now resembled a quiet, deserted stage on which they could play out any story they wished. The main attraction of the evening was to be the old warehouse on the Waterfront. Abandoned for years, with a wobbly door and a rusty sign: "No admission allowed". It had long intrigued all three of them. - 'I saw something there last night,' Michal said, glancing at the others. - I swear, it was like someone was hanging around between the crates. Maybe we'll find something interesting? - He winked, and Lena snorted with laughter. - 'Probably a rat,' she joked. - But all in all... he who doesn't take risks doesn't win! Kacper smiled half-heartedly. He was always the most cautious, but this time curiosity won out. He pushed open the warehouse door. They came through with a deafening clatter. Inside, it smelled musty and salty. Spots of light from the torch moved along the walls, revealing old barrels, crates and banged-up sacks of what had once probably been grain. Lena approached one of the crates, ran her hand over the lid and noticed a strange mark on it - carved deep into the boards, it depicted a stylised lighthouse with a flame hidden inside. - Hey, look! - she called out. - Someone had carved it here on purpose? Before Michal had time to reply, a sound like splashing water came from the depths of the warehouse. Everyone froze. A noise could be heard, as if a stream was oozing from underground under the floorboards. - 'It's just water under the foundations,' Kacper said quietly, although he did not sound convinced. They approached the corner of the room, where an old wooden door was hidden behind a pile of crates. It was slightly ajar and a cold gust of air escaped from behind it, carrying with it the smell of the sea and... something else, strange and difficult to name. Michael knelt by the door. - Shall we go? Lena nodded, clutching her torch tighter. As they stepped inside, their footsteps echoed down the narrow stone corridor that descended underground. Each of them felt a thrill of excitement mixed with anxiety. Copper pipes began to appear along the walls, leaking in places, forming puddles on the floor. A pale light winked in the distance, as if inviting them deeper. They stopped because just ahead of them, in the middle of the corridor, someone (or something) had left damp footprints leading towards the light.... - What now? - Lena looked at her friends, and her voice reverberated off the walls. The three friends stood in suspense, clustering in a tight group, listening to each other's quickened breaths, uncertain of what awaited them around the next bend.