Missing at the Sluice Gate
A foreman’s crew vanished after reporting lights below the old floodworks. The town is offering coin to anyone brave enough to search the flooded tunnels.
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In a low marsh-town built around canals, old floodworks, and sinking stone, something beneath the waterline has begun to stir. Strange tides, missing workers, and whispering dreams point to a hidden vault sealed generations ago.
The party is drawn into a web of civic panic, smugglers, and forbidden excavation as someone tries to open what was meant to stay buried. Act I focuses on the first signs of the conspiracy: investigation in the town, a dangerous descent into the flood tunnels, and a confrontation with the agent who is trying to retrieve the vault key.
Graymire Reach is a wet, leaning town of boardwalks, sluice gates, and half-sunken stone. For weeks, the rain has never quite stopped. Now boats go missing, workers vanish near the floodworks, and at night people hear singing under the water.
You begin with a simple problem: someone in town is paying for help, and the deeper you dig, the more the marsh seems to dig back.
A town official, a dockside informant, or a worried relative asks you to investigate the disappearances around the old sluice gate before the next storm tide hits.
Act I is an introductory mystery-adventure set in a canal town built on collapsing floodworks. The central pressure comes from a series of disappearances, damage to the sluice gate, and the recovery of a key fragment tied to an ancient sealed chamber below the town. Keep the pacing brisk: one social scene, one investigation scene, and one dungeon-combat scene. The villain should appear as a competent field agent rather than a final mastermind, leaving a bigger threat implied but not revealed.
A foreman’s crew vanished after reporting lights below the old floodworks. The town is offering coin to anyone brave enough to search the flooded tunnels.
A relic dealer, priest, or scholar recognizes a jade-and-brass key shard found in the mud and begs the party to keep it away from thieves.
The party investigates disappearances and sabotage in a marsh town built around failing sluices. Clues lead from the docks to flooded tunnels beneath the settlement, where a hired ritualist attempts to recover a key fragment and open a sealed chamber.
Rain drums on the planks, lanterns sway in the wind, and the canal below reflects no stars at all. A shouted warning cuts through the night as shapes move between the cargo piles.
Open with tension and immediacy. The party sees the town’s danger firsthand and gets a fast lead into the broader mystery.
Shelves rise like dark teeth above damp stone floors. Every map in the room has old water stains, and one set of records has been removed so recently the dust is still clean underneath.
This is the investigation scene. Let the party piece together the ritual history and identify the chamber beneath the town.
The air turns cold and tastes of rust. Ahead, water surges against iron grates while a robed figure lifts a jade shard over the flood channel and begins to speak in a steady, practiced voice.
Run this as the climax of Act I. Use the flooded terrain to create movement choices and let the ritual feel urgent without needing a huge battle.
Milestone: The party reaches level 2 after preventing the sluice chamber ritual or recovering the key fragment.
Veyl Thorne
Veyl Thorne is not a zealot, at least not in the way people prefer their villains. They do not rant, pray, or foam at the mouth about desti…
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Subscribe NowVeyl believes the buried vault contains a device or archive that will restore power and leverage to those willing to exploit the town’s forgotten foundations. They are desperate to recover the key pieces before rival scavengers or the authorities can interfere.
Cool, precise, and impatient. Veyl speaks like a professional doing necessary work, not a fanatic. They never waste words and treat the party as an inconvenience that can become a problem.
Veyl avoids fair fights. They begin behind cover, order their allies forward, and use the environment to slow pursuit. If the tide turns, they trigger flooding, retreat through a prepared route, or bargain with information to buy time.
If captured, Veyl can be turned into a valuable witness against the larger conspiracy. If defeated, their notes point to a deeper patron and the next act of the campaign.
Recommended party: 3-5 characters
Discuss waterborne horror, loss of control, collapsing structures, and body-horror-adjacent imagery carefully. Use lines and veils for drowning, claustrophobia, and cult imagery. Establish whether the table wants investigation-heavy play, combat-forward play, or a mix. Remind players that Act I is about stopping a local threat before revealing a larger mystery.
For 3-player or low-power groups, reduce enemy counts by one in each combat and make escape routes obvious. For 5-player or highly optimized groups, add one bandit to the first and last encounter, use more difficult terrain, and let the villain activate a flooding hazard after round 2. Avoid adding stronger monsters; use the environment instead.
Keep clues redundant: every important fact should appear in at least two places. Make the water feel like a pressure timer, not just scenery. Give the villain a clear plan and an escape route so the campaign can continue beyond Act I.
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Veyl Thorne
Veyl Thorne is not a zealot, at least not in the way people prefer their villains. They do not rant, pray, or foam at the mouth about desti…
Free campaign generations include one villain sheet. Additional villain, NPC, and player-facing module character sheets are available in premium campaigns.
Subscribe NowFree campaign encounters use official monsters only and do not include generated monster sheets. Subscribe to create custom campaign monsters and enemy stat blocks.
Subscribe NowVeyl believes the buried vault contains a device or archive that will restore power and leverage to those willing to exploit the town’s forgotten foundations. They are desperate to recover the key pieces before rival scavengers or the authorities can interfere.
Cool, precise, and impatient. Veyl speaks like a professional doing necessary work, not a fanatic. They never waste words and treat the party as an inconvenience that can become a problem.
Veyl avoids fair fights. They begin behind cover, order their allies forward, and use the environment to slow pursuit. If the tide turns, they trigger flooding, retreat through a prepared route, or bargain with information to buy time.
If captured, Veyl can be turned into a valuable witness against the larger conspiracy. If defeated, their notes point to a deeper patron and the next act of the campaign.
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Suggested Level: 1-2
- Narrow boardwalks over black water
- Mooring posts for partial cover
- Slippery planks in rain
- Canal edges count as difficult terrain when climbing
A pouch with 12 gp, a mud-stained map scrap, and a brass tunnel token.
Use this as a chase-styled opener or a quick combat. If the party is smaller, reduce to 2 bandits.
Suggested Level: 1-2
- Knee-deep water in the central passage
- Collapsed stone piles for cover
- Rusted grates that can be forced or climbed
- One section can be flooded to separate the battlefield
A flooded niche contains a silver prayer disk worth 25 gp and a clue etched on stone.
The rats should harry casters and stragglers while skeletons hold the line. If needed, remove one skeleton.
Suggested Level: 2-3
- Cranked sluice controls that can change water levels
- Waist-high flooded areas
- Catwalks over a drainage shaft
- Falling debris on initiative count 20 if the chamber is damaged
The jade key fragment, a signet ring from the town archives, and a scroll tube containing a partial vault map.
This is the Act I climax. If the party is struggling, have the fanatic attempt escape instead of fighting to the death. If they are strong, add 1 bandit.
Mudskipper Boots
Completed
Act I - Dock Ward evidence cache
False
Lantern of Still Water
Completed
Act I - Flood tunnels
False
Jade Key Fragment
Completed
Act I - Sluice Chamber ritual site
True: attunement by a creature who can cast at least one spell or has proficiency in Arcana
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