Turn 6 of 9

Go down to the fourth floor, east corridor, and look for the first door

You descend two flights, and the tower's familiar geography shifts around you as though waking up. The stairs you have climbed a thousand times feel different underfoot — not steeper, but more deliberate, each step holding your weight a half-second longer before releasing it, as though the glass is counting your footfalls and finding them sufficient. The walls here are thinner than in Yrenne's workroom, and the morning wind presses against the exterior in long, low notes, a sound like a bow drawn slowly across a bass string. The key in your pocket has not warmed to your body. It stays cold, a small rectangle of ice against your thigh, and you are aware of it with every step.

The fourth floor corridor opens before you, and you know it — you have mopped these floors, polished the glass walls, replaced the tallow lamps in their iron brackets every third day for nine years. The west corridor leads to the storage rooms and the cistern. The north corridor leads to the sleeping quarters, yours and Cassiel's, though Cassiel's door has never once closed. The east corridor is the one you have always passed through without thinking, a short hallway ending in a blank wall of black glass, unremarkable, featureless, a place where nothing has ever happened.

Except that now you are looking for something, and the corridor is looking back.

The wall at the end is not blank. You have seen it blank a thousand times — you are certain of this, the way you are certain of your own name, certain of the weight of a water bucket, certain of the smell of Yrenne's workroom. But certainty is a thing the tower seems to be quietly dismantling this morning, because the wall at the end of the east corridor has a door in it. Not a door that has appeared, not a door that has opened — a door that has always been there, with hinges sunk into the glass and a keyhole set at waist height, and you have walked past it every day for nine years and never once seen it. The glass around the doorframe is faintly discolored, a darkness in the black, as though the wall has been holding this shape for a long time and only now permits you to notice.

You stand before it. The keyhole is narrow, toothed, unfamiliar — the iron key in your pocket is the mirror of it, you know this without testing, the way a hand knows the shape of a glove. The door has no handle, no knob, no way to open it but the key. You can feel the tower's hum through the soles of your boots, stronger here than anywhere else you have stood, a vibration that is almost a voice, almost a word, almost a name being spoken in a register too low for your ears. The glass is warm to the touch when you press your palm flat beside the keyhole. Warm, and giving, like skin over a pulse.

You have served Yrenne Talo for nine years. You have polished these walls and never seen this door. The certainty that it was not here yesterday sits in your stomach alongside the certainty that it has been here for decades, and both of these things are true, and neither of them cancels the other. The key is in your hand. The keyhole waits. And somewhere above you, one floor up, Cassiel is standing in Yrenne's workroom, and the bowl of not-water is sitting on the bench between them, patient and aware, and it is watching you through the tower's glass the way a teacher watches a student approach a lesson they have been preparing for a very long time.