Here are some ideas for unique settings for mystery stories:

1. A remote research station in Antarctica during the long polar night. The isolation and extreme environment could add tension to a locked-room style mystery.

2. An underwater habitat or deep sea research facility. The claustrophobic setting and inability to easily escape or get help could heighten suspense.

3. A space station or colony on another planet. The sci-fi setting allows for unique murder methods and motives related to the environment.

4. A high-tech smart home gone rogue. The house itself could become a character and potential threat.

5. An immersive virtual reality game world. Blurring lines between the game and reality could add intrigue.

6. A remote monastery or convent cut off from the outside world. The closed religious community provides an interesting backdrop.

7. A traveling circus or carnival. The colorful characters and constant movement create opportunities for misdirection.

8. An elite boarding school for gifted students. Academic pressures and adolescent drama could fuel motives.

9. A luxury airship on a round-the-world voyage. Similar to a classic train mystery but with added peril of being airborne.

10. An archaeological dig site of an ancient civilization. Mysterious artifacts and curses could play into the plot.

11. A high-security prison during a riot or lockdown. Tensions run high with limited ability for outside help.

12. A remote tropical island resort cut off by a hurricane. Paradise becomes a deadly trap.

The key is to choose a setting that is both interesting to explore and provides unique constraints or challenges for solving the mystery. The environment should almost become a character itself, influencing the plot and heightening suspense.