The lighthouse at Osetnica had been silent for three months since the lighthouse keeper disappeared. Waves pounded against the breakwater, but the glass bowl did not shine at night. Fourteen-year-old Lena was returning from a school trial sailing, with a rucksack full of salt. On the steps of the lighthouse she found a wet notebook, tied with a thin rusty wire. Someone had written dashes and dots on the cover, like on old maps. When Lena opened the first page, the page trembled with dried salt. The next day she brought the notebook to Igor and Mila, the best puzzle hunters. The three sat in a shed by the harbour where the nets were drying. Inside were numbers, arrows and words arranged without spaces. At the end was the date of tomorrow's tide and a mysterious lighthouse sign. Igor noticed that the signs resembled the Morse alphabet mixed with a substitution cipher. Mila compared the dashes with the tide table and noted down three mysterious coordinates. In the school chronicle they found a picture of Miron Kłosa, the last lighthouse keeper of Osetnica. The caption read: "He guards the lights and the silence, even when the storm screams". Next to it, someone had added a single word in pencil, slightly blurred: "Come back, please." Lena felt a shudder, as if the photograph was looking straight through her at the sea. In the afternoon they had worked out the first line of the cipher, indicating: "open radio on silence". The radio had long since been switched off, but there was still a crank for power in the lighthouse. They went after dark, when the fog was laying low and the seagulls were silent. The stairs creaked sharply, as if the wood lacked courage and breath today. Lena turned the crank until the radio beeped and then pulsed quietly. There were short beeps in the loudspeaker, forming a familiar rhythm. Igor whispered numbers and Mila drew their course across the map of the bay. Suddenly the compass pointer twitched and stood still, as if something was holding north. Footsteps came from below, single, wet, with pauses as if in code. The door to the platform opened of its own accord and the sea responded with a third signal. On the metal railing someone had drawn the same dotted arrow in chalk. A shadow of a cloak flashed behind the glass, but the wind gauge stood completely still. The radio wailed briefly, then spat out a single word with a crackle: "Miron". Lena swallowed her saliva as a chain bolt jerked from below. The handle of the lantern moved slowly, as if waiting for their consent.