Hall of Nine Doors

RoomPuzzle RoomCult of the Thread (W18)3 exits

ruined-templepuzzle-logiclore-checkclue-rich

Illustration: Room 3 — Hall of Nine Doors

Nine doors stand in the curved far wall of this hall, identical, bronze-bound, shut. The two long walls either side of you are painted floor to ceiling in red figures on white plaster: a procession of women in double-belted skirts, each carrying a spool, each paying out a thread that runs on ahead of her along the wall.

A brazier by the entrance is still warm. Someone stood here within the hour, and they were not painting.

DM summary. Eight of the nine doors are bricked alcoves that spin the wall and scramble the order; one is the Cult's own route. The frescoes name the true door and will keep naming it, because the paintings do not move and the doors do.

Terrain & Features

Battle map: The Altar Steps — page 27, 55 × 75 ft (one half of The Grey Warrens)

The alcove hall is the nine-door hall: chalk a bronze plate in each alcove and add doorways until nine face the centre, curving the far wall with a drawn arc. The printed steps make a fine brazier platform.

Dimensions. 50 ft × 30 ft, ceiling 18 ft, the far wall curved in a shallow arc so all nine doors face the room's centre. Older masonry than the maze around it — this is a temple hall the Labyrinth was built through.
Light. A bronze brazier by the entrance, freshly banked, throwing 30 ft of dim light. There are eight more brackets and they are all empty. Someone carries the lamps around with them.
The frescoes. Two walls, thirty feet each. Nine thread-bearers on the left wall, nine on the right, all walking toward the doors. Every painted thread runs the length of the plaster and terminates at a door — the painter counted the doors and made the count come out.
The doors. Nine, numbered nowhere, indistinguishable. Each is a bronze plate on a stone frame, and each frame is a segment of a turntable that runs the whole curved wall.
The drive-arm. Under the floor, a bronze crank the length of a man turns the wall. It is audible when it moves — a slow grinding thump — and it is weeping ichor from a cracked seal at its shoulder, the pale gold stuff the Daedalan machines run on. A flask can be filled.
The scaffold. Wooden, in the near corner, four feet of it rotted. It was put up to reach the upper register of the fresco and never taken down.

Traps / Puzzles / Checks

The puzzle. Eight of the eighteen painted threads carry a knot — a small square splice, painted deliberately, the size of a thumbnail. Ten do not. Each knotted thread ends at a false door. The unknotted threads all end at the same door, and that door is the way through.

Element	Value
Seeing the knots at all	Perception DC 14, or automatic for anyone who touches the plaster — the splices are painted in relief
Understanding them	Investigation DC 13: eight knots, eight doors, one door with no knot on it. Or Religion / History DC 14: the Cult of the Thread never knots a true line. A spliced thread is a lie the Cult tells on purpose, and their splice is always square
Reading the count from the upper register	Athletics DC 10 to trust the scaffold, then no check — the top of the fresco is the clearest
Mechanical fallback	Thieves' Tools DC 16 on any door reads the lock's wear: eight locks are unworn, one is polished to brass. Takes 10 minutes and one door at a time, so a party can brute-force this in under an hour and lose the hour
Second fallback	Athletics DC 18 forces a door. It opens on an alcove either way, and the strain jams the turntable, which locks the doors in their current arrangement — which is a mercy, not a punishment, and the frescoes still work
Solved state	The true door opens on a corridor with a guide-thread already run down it at knee height, red, unbroken

Opening a false door. A 3-ft alcove, empty, floored with a bronze bell-plate. Weight on the plate rings the hall and the turntable turns one door clockwise. Nothing arrives. The doors are simply somewhere else now, and the frescoes have not moved, so the party has lost thirty seconds and nothing else. Say the grinding thump out loud every time; the sound is the lesson.

A party that never solves it takes exit A and loses nothing but the clue and the thread. Do not let this room become a forty-minute standoff — see DM Notes.

Exits

AObviousThe mason's door in the near corner behind the scaffold, half the height of a man, standing open. The workmen's way in. No check.Rider: it runs behind the fresco wall on the wrong side of the plaster and comes out low; you arrive dust-caked and bent, with disadvantage on Stealth for one room. You also never learn which door was true, and the DM skips this room's clue.

BConditionalThe true door among the nine, opened by reading the unknotted threads or by the lock-wear fallback.Rider: you leave holding a hand's length of the Cult's unspliced guide-thread, cut from the corridor beyond. It is a Sign-tier clue for X10, and once, later, it will re-tie a guide-thread somebody cut.

CHiddenThe gap where the turntable's floor-track meets the old temple paving — a foot of clearance, enough to belly through, and only open when the wall sits one notch off true. Investigation DC 15.Rider: you come out at floor level from under a wall, which is a very good way to arrive; take one Stealth check at advantage on entering the next room.

Loot

None. The hall was stripped before the Cult moved in and the Cult carries its lamps with it. The ichor from the drive-arm is worth having and is not loot: it is the good oil for a seized Daedalan mechanism, and X20 will ask for exactly one flask of it.

Scaling — APL 6 / 12 / 15

APL	Adjustment
6	The knots are painted large and gold-leafed: Perception DC 12, Investigation DC 11. All other DCs −2. The turntable only turns on the second false door
9	As written
12	Twelve doors, not nine, and two unknotted threads that both end at doors — one true, one bricked shut behind. DCs +1. The turntable turns two notches
15	As APL 12, plus the brazier's owners come back: a Thread-Warden patrol of three passes through on a six-round cadence, and the room becomes a stealth problem laid over a reading problem. DCs +3

DM Notes

Pacing: 12–15 minutes, and cap it at 20. Puzzle rooms are the ones that eat a session. Set a real limit: after 15 minutes of table time, have the brazier gutter and let a passive Perception of 12 catch the splice on the nearest thread. The party still solved it; you just handed them the magnifying glass.
If you are behind schedule, open with the knots already visible — describe them in the read-aloud as "little painted knots, one to a thread, on most but not all of them" — and run this as a four-minute room. It is a good early room precisely because it is compressible.
Do not let anyone roll to solve it. The Investigation DC 13 is for noticing the pattern, not for being told the answer. If a player says "the one without a knot", they are right whether or not anyone rolled.
The warm brazier is the room's whole threat. There is no fight here. There is the constant, un-cashed suggestion that the people who tend this hall are one corridor away and will be back. Play the sound of the turntable as something the party is announcing to them.
Clue drip. Two objects: the fresco's fourth panel on the right wall, which shows the great bronze gate from the inside with its counterweight housing drawn in cutaway — the strongest early pointer to X08 and X19 in this part of the deck — and the unspliced thread itself for X10. If your Resolution is X20, the weeping drive-arm is the ichor and the clue at once.
Callback. If your table has met the Cult of the Thread before, this is where the square splice becomes knowledge rather than decoration. A party that learns the knot here will recognise a cut-and-retied guide-thread anywhere in the maze, and that recognition is worth more than the door.