Adventure Summary: A one-session train heist and rescue for four to five 7th-level characters. An astronomer and a comet-tracking lens are being carried across the Starfall Viaduct, and the party must board the moving train, free the prisoner, and separate the vault car before it reaches a private fortress.
Brass Comet Saga: Part 3 of 4. This adventure stands alone. Previously: The Clockwork Embassy Job. The saga continues with Who Stole the Brass Comet.
Overview
Professor Lio Ardent is locked in the Observatory Car of the Midnight Meridian, forced to calibrate a lens for Magnate Orin Veyr. The city rail office offers 1,200 gp for Lio’s safe return and authorizes the party to seize the stolen lens without endangering passengers.
Track Distance from four to zero. Reduce it after each major scene or twenty minutes. At Distance 2, the train enters exposed mountain curves and roof movement costs 10 extra feet. At zero, fortress gates close around the engine, but uncoupled rear cars coast safely into Starfall Station.
Background
The route cipher from the embassy identified the Midnight Meridian. Veyr’s agents abducted Lio because only he can align the Cometline Lens. Rail Marshal Kesh believes the transport is legal, while Conductor Brann suspects forged orders but refuses to risk sixty passengers without proof.
Standalone hook: The rail office provides grappling launchers, a carriage plan, and proof that Lio’s transfer warrant is forged. Freeing Lio and uncoupling the Vault Car returns the train to lawful control and completes the mission.
Characters
- Professor Lio Ardent: A warm, stubborn astronomer who can align the stolen lens or sabotage it safely.
- Conductor Brann Voss: The train’s safety-minded commander, ready to help when shown the forged warrant.
- Rail Marshal Kesh: A disciplined officer who follows the transport order until its seal is disproved.
- Coupler Golem: A compact rail construct that guards the Vault Car connection and repairs damage.
Setting
The labeled map places the Engine, Marshal Car, Passenger Car, Observatory Car, Vault Car, and Rear Coupler in order. Interior doors are unlocked for passengers except the Observatory and Vault, which require DC 15 thieves’ tools, Arcana, or an officer’s key.
On the roof, a creature that takes damage must succeed on a DC 13 Dexterity save or slide 10 feet. A secured rope grants advantage. Falling characters catch a maintenance rail and hang safely until they use half their movement to climb back up.
Plot Outline
The party boards at the rear, crosses the Vault and Observatory Cars, proves the warrant is false, frees Lio, takes control of the stolen lens, and uncouples the occupied rear section so it reaches Starfall Station while the hostile engine continues without prisoners.
1. Catch the Meridian
The party launches grapples from a maintenance tower. Each character makes DC 13 Athletics or Acrobatics. A failure deals 1d6 bludgeoning damage but a safety line pulls the character onto the rear platform. Three total successes prevent the boarding alarm.
2. The Vault Car
The Cometline Lens rests in a shock cradle guarded by two Coupler Golems. The party can fight, use three DC 15 Arcana or tinker’s tools successes to put the golems in maintenance mode, or open the manifest safe and show that the cargo number is invalid.
3. Passengers Between
A sudden curve sends luggage across the Passenger Car. Three DC 14 Athletics, Acrobatics, Medicine, or vehicle checks protect civilians. Success earns Brann’s trust. Failure reduces Distance but Brann still listens if shown the forged warrant.
4. Observatory Lock
Lio’s door uses three moving star rings. Three DC 15 Arcana, Investigation, or thieves’ tools successes open it before two failures. Each failure shocks the operator for 2d6 lightning damage. Lio can call one correct constellation through the door, granting one automatic success.
5. Battle at the Coupler
Kesh confronts the party between the Observatory and Vault Cars while one Golem repairs the coupling. The party wins by defeating the defenders, earning three DC 16 Persuasion or Investigation successes with the warrant evidence, or completing four DC 15 Athletics, Arcana, or smith’s tools successes at the coupling. At initiative 20, the cars separate five feet unless stabilized.
6. Starfall Arrival
The freed rear cars coast into Starfall Station with every passenger safe. Brann confirms the evidence, Kesh accepts lawful review or arrest, and Lio turns over the lens after recording its readings. The lens points toward the city’s public observatory, a future lead after the train rescue and seizure are fully resolved.
NPCs and Monsters
| NPC or Monster | Statistics | Key Abilities and Table Notes |
|---|---|---|
| Professor Lio Ardent | Medium humanoid; AC 12, HP 35, speed 30 ft. | Arcana +8, navigator’s tools +9. Star Alignment grants one automatic lens or route success. He takes cover and sabotages hostile controls. |
| Conductor Brann Voss | Medium humanoid; AC 15, HP 63, speed 30 ft. | Signal baton +5, 1d8 + 3 bludgeoning. Emergency Brake changes train movement once. He allies when shown the forged warrant. |
| Rail Marshal Kesh | Medium humanoid; AC 17, HP 88, speed 30 ft. | Two shock batons +6, 1d8 + 3 bludgeoning plus 1d6 lightning. Arresting Line restrains, escape DC 15. She stands down for proven forgery. |
| Coupler Golem | Medium construct; AC 17, HP 68, climb 20 ft. | Two wrench arms +7, 2d6 + 4 bludgeoning. Repair Coupling reverses one sabotage success. Maintenance mode requires three DC 15 checks. |
Rewards
- 1,200 gp from the rail office plus lifetime first-class passage on the Midnight Meridian.
- Cometline Compass: This rare compass points toward a named vehicle or safe station once per dawn and protects its bearer from one forced movement effect per long rest.
Scaling the Adventure
For 6th level, use one Coupler Golem in the Vault Car and reduce Kesh to 72 hit points. For 8th level, add a second Golem at the final coupling. For a two-hour session, begin in the Vault Car after successful boarding. For groups avoiding high-speed falls, roof failures drop characters through open maintenance hatches into empty compartments instead of leaving them outside.
Midnight Train-Themed Table Gear
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- Fantasy armored train miniature. Lay out the car order and separate the Vault Car physically during the climax.
- Mini brass compass prop. Track Distance and present the Cometline Compass as a concrete reward.
- Mountain viaduct terrain. Supports roof movement, exposed curves, and the final car separation.