Question: **Dateline**: 2067

**Setting**: A research base at the bottom of the [Marianas Trench](https://en.wikipedia.org/wiki/Mariana_Trench)

**Depth**: 10,000 meters.

**Mission Duration**: Thirty days

A research base lies at the bottom of the Marianas Trench, housing 10-12 scientists of both sexes and a cat.

The mission starts well, the team have trained together for months, and they're tight knit. At least they thought they were...

One by one, they start to die, and it becomes obvious that their deaths are not accidental.

**Question**:

What would be a reasonable prime purpose of this research mission? For what reason would a dozen scientists be sent to the bottom of the ocean for a month where a robot/scans would not be appropriate?

Answer: 
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> What would be a reasonable prime purpose of this research mission? For what reason would a dozen scientists be sent to the bottom of the ocean for a month?
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Study of the Xenophyophores down there - we don't know very much about them and a study of how they are able to survive such immense pressures would be of plausible scientific value. Some of the ones identified as living down there are as big as 10cm across! That's pretty noteworthy.

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> What physiological reason could there be for one (or two) members of the research team to kill others, but for that same cause not to affect any other member of the team?
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Claustrophobia, particularly the Cabin fever/stir crazy form - it's a an oldy-but-a-goody. Wiki describes the symptoms of being "stir crazy" as including "elevated and often increasing levels of anxiety, frustration, agitation, fidgeting, manic depressive type mood swings, and accessory episodes of acting out impulsively or otherwise antisocially on those feelings," combined with the description on the Cabin Fever article of "a distrust of anyone they are with" and that sounds like a recipe for a bit of good old fashioned homicide amongst "friends". Not everyone is affected by these things and if a member of the team were prone to such effects and it were missed during the pre-mission pysch screenings (maybe they even lied a little to get on the mission?) it could easily only affect one or two people sufficiently to cause them to go homicidal.
I'm not curious about what the 12 scientists are doing there, I'm curious about the cat. The "cat" could actually be a prototype of an artificial lifeform designed to survive that intense pressure. Now you've got yourself a plot...

How you design an artificial lifeform to survive that pressure - you're going to have to think hard about the physics of that, because it's likely to be non-trivial.