Adventure Summary: A one-session fantasy mystery for four to five 8th-level characters. The Brass Comet vanishes from a sealed observatory during a public viewing, and the party must reconstruct the theft, recover the celestial instrument, and expose the culprit before false evidence starts a trade war.
Brass Comet Saga: Part 4 of 4. This adventure stands alone. Previously: The Midnight Train to Starfall. This concludes the Brass Comet Saga.
Overview
At dawn, the public observatory unveils a brass model that predicts the real comet’s safe sky lanes. When the dome opens, the model disappears from its locked cradle, a meridian drake appears on the roof, and evidence points to three rival city delegations.
Track Accusation from zero to four. Add one whenever the party publicly names a suspect without two supporting clues or destroys evidence. At Accusation 3, delegations prepare to leave. At 4, guards detain the nearest foreign witness, but the investigation continues and evidence can still reverse the arrest.
Background
Magnate Orin Veyr built a hollow duplicate of the Brass Comet and arranged its apparent theft. The real mechanism is hidden inside the Meridian Roof’s telescope drive, where it quietly redirects tomorrow’s sky lanes through his toll stations. He released a harmless meridian drake to create confusion and planted foreign tool marks.
Standalone hook: Inspector Dara Fenn deputizes the party, gives them unrestricted access, and promises 1,500 gp for recovering the mechanism and identifying the thief. Every clue needed to solve the case is inside the observatory, with no prior saga knowledge required.
Characters
- Inspector Dara Fenn: A fair investigator who records the party’s clue chain and prevents premature arrests.
- Magnate Orin Veyr: A charming sky-lane investor who staged the theft to validate his private toll network.
- Professor Lio Ardent: The astronomer who can distinguish the real mechanism from Veyr’s hollow display copy.
- Meridian Drake: A luminous celestial animal drawn by the hidden mechanism rather than trained to attack.
Setting
The labeled map connects the Public Rotunda, Empty Cradle, Chart Vault, Lens Workshop, Meridian Roof, and Skybridge. The observatory remains open under Dara’s authority. A DC 14 Investigation check in any location always reveals its core clue, while a higher listed check reveals an extra advantage for the finale.
Clues are redundant. The party needs any four of six: reversed cradle dust, Veyr’s private brass alloy, altered lens orders, telescope grease on Veyr’s cuff, the drake’s attraction to the roof drive, and a false foreign tool mark cut after the dust settled.
Plot Outline
The party secures the rotunda, examines the empty cradle, compares charts and workshop records, questions suspects, follows the meridian drake to the roof, proves Veyr hid the real mechanism in the telescope drive, and resolves the case by arrest, confession, or public demonstration.
1. Seal the Rotunda
Dara asks the party to preserve footprints before the crowd disperses. Three DC 14 Investigation, Survival, or Persuasion successes collect witness positions and the reversed dust clue. Failure adds Accusation, but Dara retains enough statements to show no one crossed the cradle’s outer ring.
2. The Empty Cradle
The lock is intact and the display shell weighs one-tenth of the catalog value. DC 15 Arcana, Investigation, or smith’s tools reveals Veyr’s private brass alloy inside the hinge. On a result of 18 or higher, the party finds telescope grease beneath the shell.
3. Charts and Lenses
In the Chart Vault, route ink has been overwritten toward Veyr’s toll stations. In the Lens Workshop, a duplicate order bears Sera Nox’s copied counterseal. Three DC 15 History, Investigation, or Insight successes establish the alteration happened before the public viewing.
4. Four Interviews
Dara, Veyr, Lio, and the foreign delegates each answer three questions. DC 15 Insight notices Veyr describes the hidden mechanism’s weight before anyone announces it. Presenting two physical clues makes Lio identify the telescope drive as the only machine strong enough to conceal it.
5. Meridian Roof
The drake coils around the telescope while Veyr activates the route change. The party wins by reducing Veyr to 0 hit points, calming the drake with three DC 15 Animal Handling, Arcana, or Persuasion successes, and extracting the mechanism through four DC 16 Athletics, Arcana, or tinker’s tools successes. Redirecting the telescope at the public screen automatically proves the route fraud.
6. The Comet Returned
The mechanism is restored to its cradle before the delegations depart. Dara arrests Veyr or records his signed confession, the planted evidence is withdrawn, and tomorrow’s sky lanes remain public. Lio awards the Meridian Lens, and the Brass Comet case closes with no unresolved obligation.
NPCs and Monsters
| NPC or Monster | Statistics | Key Abilities and Table Notes |
|---|---|---|
| Inspector Dara Fenn | Medium humanoid; AC 16, HP 76, speed 30 ft. | Inspector’s blade +7, 1d8 + 4 piercing. Preserve Evidence cancels one Accusation increase. She arrests only after four clues. |
| Magnate Orin Veyr | Medium humanoid; AC 16, HP 110, speed 30 ft. | Two comet cane attacks +8, 1d8 + 4 force. Redirect Lens, DC 16 Dexterity. Four clues strip his social advantage; he confesses at 25 HP. |
| Professor Lio Ardent | Medium humanoid; AC 12, HP 35, speed 30 ft. | Arcana +8 and Celestial Calibration identify the true mechanism. Call the Constellation adds 1d6 to a clue or telescope check. |
| Meridian Drake | Large celestial; AC 16, HP 95, fly 60 ft. | Two star claws +7, 2d8 + 4 radiant. Meridian Breath, DC 15 Dexterity. Three calming successes end its aggression immediately. |
Rewards
- 1,500 gp from the observatory council and public exoneration of every falsely accused delegation.
- Meridian Lens: This rare lens reveals altered routes and hidden mechanical seams, granting advantage on one investigation of a device per short rest.
Scaling the Adventure
For 7th level, reduce Veyr to 90 hit points and the drake to 80. For 9th level, Veyr gains one legendary resistance and the telescope drive needs five extraction successes. For a two-hour mystery, begin with the reversed dust and brass alloy clues secured. For groups that prefer no combat, Veyr tries to escape across the Skybridge while the drake responds only with blocking movement and non-damaging light.
Celestial Mystery-Themed Table Gear
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- Tabletop orrery model. Makes the empty cradle, route redirection, and final public demonstration easy to visualize.
- Violet magnifying glass. Represent the Meridian Lens and invite players to examine physical clue cards.
- Constellation clue cards. Organize the six redundant clues and the telescope alignment without relying on memory.