At Grandma Nina's old boarding house, above the harbour in Birch Bay, Mila was tidying up the attic. She was fourteen, with a pocket full of paper clips and a head of questions. Olek, a year older, slid a rusty compass and a dishevelled deck book out of his trunk. In the compass, the needle spun like crazy until it suddenly faced north-east. The book was missing pages, with only a page left with a salt stain and a sentence: 'Where the water plays on the steps.' - 'It's those Stone Steps by the breakwater,' said Olek, lowering his voice. Rumour had it that at low tide the stairs sing, as if the harbour were breathing. Grandma forbade going there after dark, but evening was just falling. Mila tucked the compass into her jacket, took a torch, a notebook and a short rope. They both descended the creaking stairs, passed the warehouses and headed towards the wet, tar-smelling quay. The mist drifted off the cliff like a curtain, and the waves beat with an even rhythm. The Stone Steps emerged from the gloom, wet and broken, leading beneath a rocky overhang. Somewhere below it was really rumbling, like drums hidden under old stones. The compass needle bounced abruptly sideways, straight onto an algae-covered wall. Mila noticed an old iron ear and a thin gap between the blocks. She tightened her hand on the rope and looked at Olek questioningly. - Shall we try it? - She whispered, feeling her heart speed up and her fingers slip. Olek slid the rod into the gap, pushed until the stone gave way with a groan. Cold and the smell of oil gushed from the darkness, as if from an engine room. They squeezed through into a narrow corridor whose floor was slippery with water. The torchlight trembled, shattered by the fine drizzle and dripping from the ceiling. On the wall someone had scratched: 'Do not open if...', and the letters were jagged. The rest was covered up by falling plaster, as if someone had done it on purpose. - 'Someone's been in here recently,' muttered Mila, picking up a metal nut. The corridor ended in a hall with a flooded track, like after a lost railway. A rusty draisine stood there, and the sign of a crowned owl faded on the wall. Beneath the cliff the water roared, but here it was quiet, as if they were holding their breath. Opposite them hung a heavy door with a four-disc lock, labelled with the letters N, E, S, W. Suddenly the compass needle began to tremble, the torch went out for a second, and a whisper sounded behind their backs: 'Mila, Olek...'.