Fog lay over the fjord like a woollen cloak, and salt settled on the lips like sugar. In Skjaldvik, a settlement sandwiched between rock walls and a narrow beach, a new boat was being built. Men were riveting planks, women were boiling tar and children were running around with buckets and handfuls of linen yarn. Hammers rattled, seagulls shrieked and the smoke from the hearths smelled of resin. - 'Just a bit more, Ivar! - cried Sigrid, lifting a beam washed up by the waves from the sand. She was twelve years old, her hair braided into two thick pigtails and a gaze that didn't glide over things but looked beneath them. Ivar, two years younger, arrived with a circle of hemp on his shoulder. He was fast, impatient and believed that the best roads were those not yet drawn on any map. - 'Torbjorn said he saw an orca by the rocks yesterday,' he wheezed. - And that a song can sometimes be heard in the ice in the north. Old Torbjorn was sitting nearby on a crate, chiselling at wood with a knife. Drops of mist dripped from his grey beard; around his neck he wore a string of amber and seal teeth. He looked at the children from under his bushy eyebrows and smiled in such a way that wrinkles formed around his eyes like rays. - A song? - Sigrid repeated. - What song? - One that stirs the wind,' he muttered. - 'Long ago, before your father Harald put up his first boat, there lived a sailor who brought a silver horn from the north. Once he blew it and the storm subsided. He blew a second time and the currents served him like a harness. - He sighed. - The third time he didn't make it because the horn disappeared into a cave under the ice. Sometimes the sea itself gives back what it has taken. - Strange tales for children! - burbled Harald, passing by with a bundle of fresh boards. He was as strong as a young oak tree and usually spoke only as much as necessary. - Instead of listening to a tale, carry what you need and stay away from the lower caves. The tides are treacherous. Sigrid nodded, though a spark of curiosity ignited inside her. Ivar squirmed but said nothing. At the cliffs it was indeed tricky: the water came up and down like the breath of a great creature, revealing the stone shelves for a moment, only to cover everything again in an instant. In the evening, the storm swept through the fjord like a bard through a common room - fast, loud and with a bang. During the night, the gale tore up the fog, and in the morning the water dropped exceptionally low. The rocks, usually covered by waves, glistened wet and shiny. The moss smelled like a freshly cut apple. - 'Ivar,' Sigrid whispered, standing over the edge of the soft path leading down towards the caverns. - See. Where foam usually bubbled up, a wide gap now blackened. A chill flowed from within it, and at the bottom, far away, something flashed with a silvery glow, as if someone had spilled moonlight across the stones. - Just for a moment,' Ivar decided. - Before the water returns. They slid down the slippery boulders, clinging to the curved roots like handholds. Their hands were cold, but their eyes were hot with takeover. The cave breathed along with the sea: with each crash of a wave in the distance, a quiet murmur vibrated in the air. They went deeper, where the walls were smoothed by hundreds of winters and summers, and the ceiling glittered from the drops as from a sky full of stars. Gently bluish algae shone across the porous stones. At the very bottom, in a niche, lay an object wrapped in hardened leather, and beside it, a stone slab with engraved markings. - 'Ró... runes,' Ivar said with difficulty, listing the letters like tidbits. - Some I know from Torbjorn's common room. Sigrid crouched down and touched the crust of the skin. It was cool and smooth. She carefully undermined the edge with the knife she usually used to cut off the dry burrs of hemp fibre. The skin let go and a shiny metal emerged from under it. Not ordinary steel or bronze. Silvery, but not cold, as if a warmth smouldered inside. - A horn," she whispered. - A silver horn. For a brief moment they were both silent, as if someone had lowered furry curtains over their words. The horn was not large; it fit the hand like a stump to a chisel. Thin engraved marks glittered at the edge - waves that passed into wind, wind into bird's wings. - Don't touch! - Ivar grabbed his sister's sleeve, but it was too late. Sigrid lifted the horn, and the metal trembled in her fingers, as if she had just woken up. A sound came from the depths of the cave. Quiet, almost inaudible, but clear as a freezing drop. The sound was not like a trumpeting, more like a single whisper of the sea. The runes on the stone slab shone brighter for a moment, as if a candle flame moved in the wind. - 'Sigrid,' said Ivar in a trembling voice. - Do you hear? Sigrid nodded. The hardwood trembled under their feet - to the rhythm of some distant thump. They looked quickly towards the entrance of the cave. Where the mist had settled, a ribbon of light cut through the mouth of the cave, and something dark moved above it. They climbed to a ledge from which the fjord could be seen. The water was beginning to return, slow and determined. On the surface, quiet as a fox, a longboat glided by. Its sail was the colour of night, and on the dragon's forehead was carved the mark of a cracked moon. - 'The Ravens of Frost,' Ivar whispered, recalling Torbjorn's stories whispered around the campfire. - He said that their sails did not rustle and that they always sailed against the wind. The boat was not from their settlement. There was no laughter, no singing, no oar slapping against the side. Just the quiet gliding cut of the water, like a knife going through the skin of milk. Several silhouettes could be seen on the deck, motionless as statues. - 'We must warn Skjaldvik,' Sigrid said. - Father is on the quay. At the same moment the horn in her hands trembled again, as if answering an echo from afar. A low murmur came from the fjord - not a thunder, not a growl, but a sound so even and deep that you could feel it in your bones. The black-sailed longship seemed to accelerate. - Put it down! - Ivar tried to snatch the horn from his sister, but Sigrid took half a step back, feeling the metal barely fit in her hands. Three marks shone in a line on the stone slab by their feet. The first like a wave, the second like a feather, the third like.... flame? The water broke into the cave more violently. The lowest ledge disappeared beneath the mirror, and a cold splash reached their ankles. Between the drops, Sigrid heard another sound - soft but heavy, like a step on wet sand. - Someone is here - Ivar looked deep into the cave. In the sinewy glow of the algae, they could see the outline of a silhouette. The figure wore a damp hooded cloak over her shoulders. She stood in the shadows, so that her face could not be seen. She stopped at a slab of runes and placed her hand over the markings without touching the stone, as if she was listening to see if there was something beating inside. Outside, the longship approached the quay. Someone on board raised their hand and gave a sign. The usual sounds of work could still be heard in the settlement - no one had noticed the black boat yet. - Sigrid... - Ivar spoke voicelessly for a moment. - What are we doing? Sigrid tightened her fingers on the silver horn. She felt a gentle, persistent tremor under her skin, like ants running over her hand. Her heart thudded in her chest like a drum. The figure in the hood raised its head. Something metal flashed in the light reflected off the damp wall - perhaps a ring, perhaps a buckle. The hood moved, and a quiet voice came from the darkness: - Leave the horn. Or use it. But decide now, for the sea will not wait. At the same moment, a draughty, shudder-inducing tone sounded from the fjord, and the shadow of a black sail moved across the cave entrance like a cloud obscuring the sun.