Adventure Summary: A one-session horror dungeon expedition for four to five 7th-level characters. The party descends into a tidal cavern to retrieve a stolen reliquary, explores an abbey hanging upside down above rising water, and escapes before its chains tear free and drag the coast into the depths.
Drowned Bell Saga: Part 3 of 4. This adventure stands alone. Previously: Pilgrims of the Salt Road. The saga continues with When the Drowned Bell Rings.
Overview
A sinkhole opens beneath Whitecliff Chapel and exposes stairs spiraling into a sea cavern. Below hangs Saint Orra’s lost abbey, inverted on six corroded chains. A reliquary stolen from the chapel glows in the abbot’s chamber while water rises one level every thirty minutes.
Track Tide from one to four. Add one after each failed major obstacle or thirty in-world minutes. At Tide 2, the scriptorium floods. At Tide 3, the chain bridge sways and ranged attacks across it have disadvantage. At Tide 4, the escape sluice opens automatically and the finale begins with falling stone.
Background
Brother Neris, last librarian of the sunken abbey, stole the reliquary in death because it contains the names that keep the Drowned Bell asleep. The Chainbound Abbot wants those names erased so the bell may ring beneath the coast. Neris will return the relic if the party proves the living still remember what the abbey was built to contain.
Standalone hook: Whitecliff’s sexton offers 1,000 gp for the reliquary and explains the Tide clock, the known rooms, and the escape sluice. Recovering it and leaving ends the adventure completely.
Characters
- Brother Neris: A nervous ghost librarian who rearranges books to communicate and wants the abbey remembered accurately.
- The Chainbound Abbot: A drowned tyrant who offers safe passage in exchange for one living name, then attacks anyone who refuses.
- Tidal Sentinels: Stone saints that animate when water touches their faces and stop when shown the open reliquary.
Setting
The cutaway map connects the Tidal Stair, Hanging Cloister, Flooded Scriptorium, Chain Bridge, Choir Well, Abbot’s Reliquary, and Escape Sluice. Gravity follows the cavern, not the inverted building, so floors become ceilings.
A fall from a hanging room drops 20 feet into water for 2d6 bludgeoning damage, halved by a DC 14 Dexterity save. A secured climbing line prevents the damage but not separation from the party.
Plot Outline
The party descends the Tidal Stair, bargains with Neris, searches the flooded scriptorium, crosses the chain bridge, retrieves the reliquary, confronts the abbot at the Choir Well, and escapes by stabilizing or opening the sluice.
1. The Hanging Cloister
Brother Neris spells ‘REMEMBER’ by dropping books upward from the inverted shelves. A DC 14 Arcana, Investigation, or Persuasion check convinces him to mark the safest route. Failure raises Tide, but he still points toward the scriptorium and warns that the abbot cannot touch the open reliquary.
2. Flooded Scriptorium
Three Tidal Sentinels guard a ledger behind floating desks. Characters can fight, open the reliquary’s empty outer case with a DC 15 thieves’ tools check to pacify them, or collect three name tablets with DC 14 Athletics and Investigation checks. Each tablet gives one automatic success against the abbot’s bargain.
3. Chain Bridge
Crossing requires four total DC 15 Acrobatics, Athletics, or mason’s tools successes before three failures. Each failure deals 1d8 bludgeoning damage and moves the character 10 feet. Cutting a counterweight lowers the DC by 2 but raises Tide immediately.
4. The Choir Well
The Chainbound Abbot begins with two Sentinels and demands one living name. The party wins by reducing him to 0 hit points, presenting three name tablets with three DC 15 Religion or Persuasion successes, or opening the reliquary and holding it within 10 feet for three rounds. At initiative 20, rising water shifts every unsecured creature 10 feet toward the well.
5. Escape Sluice
The abbot’s defeat releases the reliquary and stops the abbey from tearing free. The party opens the sluice with three DC 14 Athletics, Arcana, or thieves’ tools successes and rides the draining current to Whitecliff. Failure costs 2d6 bludgeoning damage but still expels them safely. Returning the relic earns payment and closes the sinkhole.
NPCs and Monsters
| NPC or Monster | Statistics | Key Abilities and Table Notes |
|---|---|---|
| Brother Neris | Medium undead; AC 12, HP 36. | Investigation +7, Religion +6. He moves books telekinetically and gives advantage on one check to navigate the inverted abbey. |
| Chainbound Abbot | Medium undead; AC 17, HP 105. | Chain crozier +7, 2d10 + 4 necrotic. He bargains at 30 HP and cannot approach an open reliquary. |
| Tidal Sentinel | Medium construct; AC 18, HP 58. | Stone oar +6, 2d8 + 3 bludgeoning. It becomes incapacitated while shown the open reliquary. |
Rewards
- 1,000 gp and safe lodging at Whitecliff Chapel.
- Sluicekeeper Key: This uncommon iron key grants advantage on checks to operate locks, valves, and floodgates. Once per dawn, it opens or closes one nonmagical valve or water-control mechanism within 30 feet without a check.
Scaling the Adventure
For 6th level, reduce the abbot to 85 hit points and use one Sentinel in the finale. For 8th level, give the abbot one legendary resistance and add a third Sentinel. For a shorter game, give Neris the scriptorium ledger immediately. For groups avoiding claustrophobia, describe the cavern as vast and keep every escape route visible on the map.
Flooded Dungeon-Themed Table Gear
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- Hanging-chain dungeon terrain. Makes the abbey’s vertical routes and unstable bridge visible at the table.
- Underwater ruins battle mat. Supports the flooded scriptorium, Choir Well, and rising Tide zones.
- Three-way iron key prop. A tactile stand-in for the Sluicekeeper Key and the final escape mechanism.