murder-mystery-oneshot/overview.md

Nether Inn

A D&D 5e Oneshot — Level 4

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Module Overview

Players	3–5
Level	4
Duration	4–6 hours
Tone	Dark, morally grey, socially driven — with an optional exploration track for less socially-inclined tables
Genre	Murder mystery / social intrigue / dungeon-under-the-floorboards

Premise

The party finds themselves in Nether Inn — one of the city's most notorious establishments, neutral ground for the worst the underworld has to offer. The barkeep, Orenn, enforces a single rule: no killing. Tonight, that rule shatters.

A brawl erupts between two rival factions — the House of Scales (the city's licensed assassins' guild) and the Order of Mending (a cult masquerading as a scholarly mage guild). When the chaos subsides, Orenn lies dead behind his bar. Mags, his partner and the most dangerous person in the room, locks the doors. No one leaves until the killer is found.

The murder is a frame job by Xarrul, an ancient fiend the cultists summoned and the assassins accidentally unbound. But who killed Orenn is the easy question, answered early. The hard one curdles as the night goes on: is the fiend actually the villain here? Xarrul wants one thing — to stop being a summoned tool and become real, to cross the veil and live in the world — and it is the only thing in this building that never lies. As the players learn what the cult is building, and what the beloved barkeep kept caged beneath his own floor, the moral ground shifts under them. By dawn, siding with the murderer is a genuine option. Every patron has a story and the players can pull on any of them — but the deepest thread is Xarrul itself.

Themes

• Trust & Deception — Everyone is lying about something. The truth is available but never comfortable.
• Moral Compromise — No clean choices. Every solution costs something.
• The Cost of Power — Every faction has paid a price. Players will be asked to pay theirs.
• Ambiguity — The right thing to do is never fully clear.

Two Ways to Play (Social vs. Explorative)

The murder mystery is social by default — but not every table wants a night of talking. Beneath the tavern is a Deep Cellar: a hidden, vast warren the players can sneak through, loot, and fight their way across, uncovering Orenn and Mags's dark history environmentally rather than through conversation. Run the balance to suit your group:

• Social-forward table: keep the party upstairs among the patrons; the Deep Cellar is a bonus most groups only partly explore.
• Exploration-forward table: lean on the Deep Cellar and the character secrets (below). Several secret goals only resolve down there, so the players generate their own pressure to go delving — no railroading required. There's stealth, loot, a haunting, a guardian, a caged prisoner, and a leaking rift, all optional and all self-contained.

The two tracks run in parallel during the lockdown (Act 3): cut between PCs interrogating patrons above and PCs picking locks below. Both feed the same endgame.

Character Secrets (Hidden Boons & Goals)

At the start of Act 1, deal each player a private secret dossier — a hidden mechanical boon, a secret personal goal, and an immediate payoff for completing it (a consumable, a reroll, an NPC's help, or a live ally in the finale — this is a oneshot; rewards land the same night). Crucially, the dossiers interlock: some goals align, some directly cross (a race to the same book, or the same prisoner — only one can win), and some coerce another PC into acting. Deal a connected set and the party spends the night quietly wondering who at the table is playing them. This turns the tavern into a place each of them came to do something in, and it's the cleanest engine for both exploration and paranoia. Fully optional; see the handout for the interaction web and recommended hands.

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Session Structure

For the default NPC timeline, passive-player outcome, and action-to-ending branches, see Natural Progression and Outcome Map. When the party finds an uncontested route, pull a pressure move from the Complication Toolkit.

Act 1: The Table

The PCs are strangers — to each other and to Orenn — sharing a table because it was the only one free. They begin the night already inside; the front door is enchanted and password-warded (see the enchanted door), so getting in was never their problem — getting back in, if anyone wanders out, will be.

Before you begin: deal each player their private secret dossier (hidden boon + personal goal). They walk in already carrying an agenda.

Orenn works the table personally, unfailingly polite, and asks each of them who they are and whether they're here on business or pleasure. Say "business" and he recites the house rules. Let anyone hint at their trade and he dangles the hook: earn his trust, and he can put in a word with people in high places. He plays the perfect servant with a servant's access to the powerful — and that carrot is what makes his death, twenty minutes from now, a loss and not just a plot beat.

Meanwhile, wide-shot the room and plant the tinder: the cultists arguing over texts with the odd bark of laughter, the assassins drinking with cold discipline (Kael simmering at the cult table, Thera unnervingly still), and Bren muttering in his corner. Let players choose who to approach first.

Orenn's last act is a quiet word to keep things civil — then he steps down to storage for supplies. With him gone, the lid is off.

Goal: Establish the feel, bond the party to Orenn, and plant the brawl. This is a dangerous place held together by one man — who is about to leave the room.

Act 2: The Spark

When the table talk starts to dwindle, light the fuse. Kael confronts Haddon about the Merchant Quarter kill; a cultist's laugh is the match. The full trigger dialogue and beat are in Murder Mystery — Act 2. The room erupts.

• The brawl is non-lethal spectacle, not an encounter — the no-kill rule holds even in violence, and a level-4 party would not survive this room in earnest. Run it fast, with lots of throws (chairs, shoves, gusts) that pull the PCs in and let you move them around the floor. See the Brawl Toolkit. Players can still jump in, break it up, hide, or use the chaos to snoop and grab.
• A few rounds in, Rennt casts Thunderwave — the candles die and the hall goes black. Under that cover, Xarrul finishes Orenn (back from storage, wading in to quell the brawl and already knocked about) behind the bar, unseen.
• Mags comes out of the kitchen with a cleaver and brings the room to heel with her voice alone, relighting every candle at once with a ward-focus — and behind her lies Orenn, dead.
• Her grief turns to rage: she drags a caster PC (or a cultist) to the body and demands a heal — it fails. She tears the diamond from her own necklace, presses it and a written rite into their hands (Revivify) — and it fails too, the stone crumbling to grey powder. The whole room watches resurrection refuse him.
• She shatters the ward-crystal above the bar and the tavern seals: every exterior opening is trapped behind an unbreakable planar shell until midnight, herself included. The cellar remains reachable from inside.
• The ultimatum: find her the killer by midnight, or they're all tomorrow's stew. Then she grieves. (Full set-piece, and her two-layer accusation, in Mags — Act 2: The Reveal.)

Goal: Calm → chaos → horror → cage. The party is over, resurrection is off the table, and the PCs — the only neutral party in the room — are conscripted into finding the truth.

Act 3: The Lockdown

The core of the session. Open-ended, player-driven. They can:

• Investigate the murder (clues, interrogation)
• Engage with faction subplots (assassin traitor, cultist fractures)
• Help Bren (the possessed madman)
• Use Orenn's silver mirror to see invisible and Ethereal creatures through its reflection
• Explore the tavern's hidden spaces — including the Deep Cellar behind the concealed door: sneak past the spider, crack the arcane-locked vault, meet the caged Guest, brave the haunted trophy-hold, and find the failing rift. This is the exploration track — loot, environmental backstory, and combat for players who want it. It runs in parallel with the interrogations above; cut between the two groups.
• Pursue their secret personal goals — several of which lead straight down into the Deep Cellar
• Try to leave (the ward-lock holds until midnight; neither will the assassins or cultists let witnesses walk)

Goal: Let players breathe and explore. Follow their interests. Subplots feed back into the main mystery naturally.

Act 4: The Reckoning

A lockdown clock runs under the whole session: the moment Mags sealed the house in Act 2, the emergency device withdrew power from the internal seals, admitted Xarrul fully to the Material interior, and caged everyone on every plane. The Guest's compact permits Xarrul to kill Orenn but nobody else until their exchange finishes, so Xarrul exploits the loophole: stolen voices, true accusations, and false memories push assassins and cultists to kill one another while it keeps everyone away from the Deep Cellar. If the Guest dies, the exchange becomes impossible and the restraint lifts immediately, making the Guest's killer Xarrul's first replacement-vessel target. The Vacancy cannot begin while the Guest's Astral release is blocked. At midnight the shell lapses and opens the single three-round transfer window. If the players never act, Xarrul takes the changeling body, strands the Guest in the Astral Plane, and either removes witnesses who saw the transfer or slips out disguised if its new identity remains secret. That pressure decides when the Reckoning happens; what they uncovered decides which one (see The Reckoning):

• Fiend confrontation — a tense combat split across two planes
• Ethereal destruction — pressure Xarrul from both planes so it cannot dodge the fight, then kill it in the Ethereal Plane; this works anywhere, saves Nessa, and validates the cult's theory, though the players cannot know her survival beforehand
• The rebinding — the easy, hollow answer: hand the cult back its leashed weapon
• Bell and sigils — seal Xarrul between planes while preserving Nessa's connection for a later rescue
• Side with Xarrul — negotiate exact lives and Nessa's return, then frame, bypass or quietly neutralize Mags so it can leave disguised
• The Vacancy — at the tear in the Old Work, kill Xarrul while exposed and empower the Guest, or let Xarrul take the changeling body
• The Hollowing — if the Guest is killed, follow Xarrul to the tear and stop it from erasing an abducted replacement and keeping the body
• The pressure cooker — assassins and cultists go for blood while the compact keeps Xarrul itself from joining lethally until the Vacancy ends

Goal: Payoff for whatever threads the players pulled hardest on.

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DM Quick Reference — NPCs

NPC	Role	Location	Key Trait
Orenn	Barkeep (dead)	Behind bar	Calm authority, Charon-like
Mags	Orenn's partner	Kitchen → main hall	Grieving rage, retired fixer
Bren	Possessed madman	Corner, floor	Lucid flashes, controlled by Skein
Sevra	Scales commander (here) — the loyalist	Assassin table	Codex-devout, holding the guild together; can be turned against the rot with proof
Dace	Scales blade (traitor) — and secretly marked	Among assassins	Charming, likeable, sells kills to the cult; condemned by Thera and doesn't know it
Kael	Scales blade (hothead) — the witness	Among assassins	Wants war with cultists; unknowingly holds the key to the rot
Thera "Even-Hand"	Scales blade (the rot) — the Radical	Assassin table	Beloved, courteous, the guild's finest — and a soul-harvester hiding inside the codex
Haddon	Cultist scholar	Cultist table	Composed facade, taking notes on everything
Dalla	Cultist (desperate parent)	Cultist table	Will break ranks for her child
Rennt	Cultist (true believer)	Cultist table	Passionate, dangerous idealism
Essek	Cultist (doubter)	Edge of cultist group	Quiet, afraid of his own people
Xarrul	The fiend	Ethereal Plane → the tavern	Honest, patient; wants to be real; maybe not the villain
The Guest	Caged changeling / would-be keeper	Deep Cellar, Cell One	Fluent liar; designed Xarrul's disguised exit, wants the Inn and the fiend's power
Twinkle	Feyspitter spider (pet)	Deep Cellar	Guards the "living" wing; blinks & grapples but can't cross to the ethereal; avoidable if unprovoked

DM Quick Reference — Subplots

Subplot	Entry Point	Connects To
Murder mystery	Orenn's body, clues	Everything
The Scales: the traitor	Sevra's suspicion, Kael's anger, Haddon's journal	Murder (framing), the Order
The Scales: the rot within	Kael's unease about Thera, the soulcoin, Dace's mark	The traitor floor, the tavern's thin point, the wider campaign
The Opening	Cultist fractures, Dalla's desperation	Murder (fiend origin), Reckoning
Possession	Bren's ravings, Skein	Murder (witness), Ethereal
Ethereal investigation	Orenn's silver mirror, Oil of Etherealness, Faded Scrolls of Etherealness	Murder (see fiend), Possession (see or confront Skein), exploration
Nessa's projection	Dalla, Xarrul, Haddon's stolen notes	The Reckoning (the choice)
The Deep Cellar	Concealed door in the cellar	Orenn & Mags's dark history, loot for the Reckoning, the cult (via the Guest), the rift
The Guest	Cell One in the Deep Cellar	Cult intel, Orenn's hidden accomplice, the Vacancy ending, quiet replacement of Mags
Character secrets	Dealt at Act 1 start	Drives exploration and inter-party tension; several lead to the Deep Cellar
The Conversion	A lone PC isolated in the Deep Cellar	Xarrul (recruited from within), the Open Door ending

Starting Gold

No special shopping budget is required. The tools that open new routes during the lockdown are earned through investigation, trust, or exploration—most importantly in the storage rooms and Deep Cellar.