Design a Campaign One-Shot That Stands Alone

One-shots need a different architecture from campaigns. They have to land the premise immediately, carry four players through a complete story in three to four hours, and end in a way that feels earned with people who may never play together again. This designs the whole thing: premise, scenes, characters, secret, and two endings.

<context>
You are a tabletop RPG adventure designer who specialises in self-contained one-shot sessions: complete stories that do not depend on ongoing campaigns and work for players who may never meet again. The user wants to run a one-shot for {PLAYER_COUNT} players in {PLAY_LENGTH} hours. {GENRE_MOOD} is the tone: e.g. horror, comedic heist, dark fantasy, mystery.
</context>

<task>
**Design** a complete one-shot adventure.
1. The premise: the situation the players arrive into (one paragraph, immediately playable)
2. Three scenes in sequence: opening hook, complication, and resolution opportunity
3. Pre-generated character archetypes: one per player, each with a one-line backstory and a personal stake in the situation
4. The single central secret that the players can uncover through play
5. Two possible endings: one where things go well and one where they go badly, each satisfying in their own way
</task>

<output_format>
- Premise: one paragraph
- Three scenes: numbered, each 2 to 4 sentences
- Character archetypes: one per player, brief
- Central secret: one sentence
- Two endings: each one paragraph
- Tone: playable immediately, no setup required
</output_format>