The school at night was very different from during the day. The long corridors seemed endless and the lights left strange shadows on the walls. Kacper and Lena stayed after lessons because they had to finish a chemistry project, but they had long since finished - now they just wandered around the empty floors of Gymnasium 7, looking for adventures. - 'Why don't we go to the old biology room? - suggested Lena, lowering her voice, as if she feared that even the echoes might hear them. Kacper looked at her with a little concern. Everyone knew that no one had gone in there since the strange accident years ago. But curiosity was stronger than fear. They crossed the corridor, dodging the puddles of light coming from the non-functioning fluorescent lights. The door to the biology room was locked with a rusty lock, but Lena noticed a soft, greenish light coming from under the door. Suddenly, they heard a quiet, scratchy sound, as if something was scratching the board from inside. They both held their breath. Lena squeezed Kacper's hand. The boy pulled a torch from his pocket and turned the door knob, which to their amazement - gave way without any resistance. - Do you hear that? - whispered Lena. The sound grew louder and the light from behind the door pulsed stronger and stronger. They opened the door a few centimetres, trying to see what was inside. Then a shape emerged from behind the darkness that neither of them expected....