The Summoning Dark at Koom Valley

Fictional record. This page describes an incident from a fictional setting, not a real event. Information is based on the cited canon, with adaptations and interpretation distinguished where necessary. It is kept separate from the real MineArchive corpus — see Fictional.

Date	Not dated (contemporary with the events of Thud!)
Mine	Koom Valley
Primary type	Flooding / Inundation
Associated types	Entrapment, Other
Fatalities	0 (No one was killed in this incident, unlike the ancient tragedy at the same site; the danger was to Vimes himself, not to anyone he encountered while possessed.)
Injuries	Vimes underwent what is described as a near-death experience during the fall and possession, and was left with the Summoning Dark's symbol etched into him as a permanent scar, later shown to the Low King's captain as proof of what had happened.
Context	Post-closure — exploration (The cave had been sealed, in effect, for roughly fifteen hundred years; Vimes entered alone, ahead of his own search party, rather than as part of any organised exploration.)
Status	Researched

Investigating alone at Koom Valley, Commander Vimes dropped into a flooded tunnel beneath the cave where the ancient dwarf-troll tragedy had taken place, and was possessed there by the Summoning Dark — the same malevolent spirit he had been infected by earlier in the case. He was found and subdued by Angua and Sally before the possession could run its course, inside the very mine the spirit's targets — Deep-Downer dwarfs attempting to destroy the site's evidence — were working in.

Cause

Vimes located a cave entrance matching his wife's copy of the old painting 'The Battle of Koom Valley', judged correctly that this was where the recovered talking cube had originally been found, and — without waiting for the rest of his search party to catch up — dropped into the tunnel and the water below it alone.

Contributing factors

Vimes was already carrying a dormant infection of the Summoning Dark, picked up earlier in the investigation from a cursed door bearing its symbol; entering the flooded tunnel alone, exhausted and under pressure to solve the case before a renewed dwarf-troll war could break out, left him without anyone to intervene quickly once the Dark took hold.

What happened

Having matched the cave entrance to his wife Sybil's copy of the old painting, Vimes recognised it as the place the recovered talking cube had come from, and dropped down into the tunnel and the dark water beneath it before the rest of his party arrived. He came to on a dark beach somewhere below, in what is described as a near-death experience, with his own organiser device — the Gooseberry — telling him he had only minutes left to make it back in time to read to his son as he had promised. Pressing on, he emerged, no longer fully himself, into a mine where dwarfs — the Deep-Downers who had come to destroy the site's evidence — were at work, and began advancing on them possessed by the Summoning Dark, demanding, in the words of his son's favourite picture book, 'Where's my cow?' Sally arrived to help contain him as the dwarfs scattered. As Vimes reached the target of his possessed pursuit, something in him stopped: his own inner sense of himself — later given the name the Guarding Dark — confronted the Summoning Dark directly and refused to yield to it. He was brought back to himself by Angua, who tackled him, and came to surrounded by the Low King's own dwarfs.

Real-world mining concepts used here: Inrush

Rescue & recovery

Sally reached the scene first and helped contain Vimes as he advanced on the Deep-Downers; Angua physically tackled him, ending the episode. He was not otherwise rescued from the water or the tunnel itself — he had made his own way through under the Dark's influence.

Investigation & inquiry

No formal inquiry was held. Bashfullsson, the philosophically-minded grag travelling with Vimes's party, explained to the others afterward that Vimes had been possessed by the Summoning Dark but had beaten it himself.

Aftermath

The Low King's own captain, on seeing the Summoning Dark's symbol left scarred into Vimes, agreed to treat Vimes's troll and non-dwarf officers, Detritus and Brick, better than he otherwise might have. More broadly, the talking cube recovered from the site was played back publicly soon after, revealing B'hrian Bloodaxe's own account of the ancient flood and defusing the immediate threat of a renewed dwarf-troll war.

Consequences

No change specific to mining law or practice is described. The wider consequence was political rather than regulatory: the revealed truth about the original tragedy undercut the case for renewed conflict that the Deep-Downers' faction had been building toward.

Memorials & commemoration

The site itself became the memorial — preserved and then resealed by trolls and dwarfs working together, rather than marked with anything separate.

Recorded claims

Each claim is marked with its basis — explicit canon, MineArchive inference, adaptation only, or fandom interpretation — and attached to the source(s) below. Where tellings disagree, both are kept.

Vimes identified the cave entrance from his wife's copy of an old painting and dropped into the flooded tunnel below alone, ahead of the rest of his search party. (explicit canon) ¹
Vimes was possessed by the Summoning Dark while in the cave and advanced on the Deep-Downer dwarfs working there, echoing a line from his son's favourite picture book. (explicit canon) ¹
Vimes's own inner sense of self, given the name the Guarding Dark, refused to yield to the Summoning Dark from within; he was physically brought back to himself when Angua tackled him. (explicit canon) ¹
The Low King's captain agreed to treat Vimes's non-dwarf officers better after seeing the Summoning Dark's symbol scarred into him; the cube's public playback soon after defused the wider threat of renewed dwarf-troll war. (explicit canon) ¹

Sources

(primary canon) Thud! — Terry Pratchett, 2005 (Discworld #34)

Record created: 25 August 2026 · Last researched: 25 August 2026