Karst Keep has eight cellars. They are numbered on the doorframes in old paint, and any clerk can tell you what each was for. Salt. Root. Ice. Wine.

There is no ninth. Two hundred and six years ago a mason put his pick through the back wall of the eighth, and behind it was a door, and behind the door was not a room.

It was a mouth.

What lies past it goes deeper than the keep stands tall and outward under half the province. Limestone, water-carved, lightless — and in long stretches not natural at all. Worked walls. Cut stairs. Doorframes standing in bare rock with nothing on either side of them. Somebody built in the Ninth long before anyone thought to knock, and nobody has established who.

It is the richest hole in the world and it has the receipts. The shallow levels pay — sword-steel that will not dull, mail that folds into a coat pocket, half the named items in circulation — and often enough that there has been a camp outside the keep gate for six generations, with a tavern and a graveyard that has nobody in it.

The people in that camp will also tell you, for a drink, exactly where to stop.

Every map of the Ninth sold at that gate is a copy of one of four originals, and all four end in the same place: a shelf of rock above a drop, four descents down, unmarked. No guild charter underwrites a party past it. Everything said about what lies below is rumour — bad air, flooding, collapse, a thing in the dark — because rumour is what you get when nobody comes back to correct it, and in two hundred and six years nobody has. Not one.

None of it is secret. It is printed on the maps.

Nine days ago Helde went over the shelf anyway, and took two women with her. The Heartstone is worth more than the three of them will earn in their lives, and they were willing to bet those lives at two centuries to nothing.

They are not going back up the way they came. That route closed on the sixth day, behind them in the dark, and none of them has said so out loud.

At the bottom of everything there is a furnished room. A table. A chair the right size for a person. A lamp, still burning. Two hundred years of expeditions have carried their gear down here and none of it has left.

That was forty-one minutes ago. It is over now.

The room has no air of its own and smells of spent mana and hot metal and the inside of somebody's helmet. Nothing in it is standing but you.

Helde is closest, face down, one arm under her, the other still strapped into a shield whose buckles have fused. Her breastplate is split along the left seam. She is enormous, breathing like a bellows with a hole in it, and every half minute gets a knee under herself before it goes out again. She has not stopped trying and will not until she stops being conscious, which will be soon.

Rivena is on her back where you put her, both blades six feet away and out of reach. Her leathers are opened across the ribs, her braid has come apart, her right arm lies at an angle it should not. She is awake, glaring at the ceiling, swearing quietly and steadily — the way people do when it is the only part still working.

Elindra never made it off her knees. She has folded onto her side against the wall, robes soaked through and clinging, hands open and empty — no mana in them for half an hour, nothing left to be frightened with. Her eyes are open. They are on you, and have been the whole time.

They came for the stone. They said so out loud, early on, before they understood you could hear them.

You stand over them and take your time. There is no reason left not to.