Descend into a undersea hive city to extract a psyker who's potentially as valuable as he is dangerous. This is an unsanctioned operation, so you need a good cover story, a solid plan, and steadfast faith in the Emperor.
This adventure is [adapted] for the d100 "Imperium Maledictum" game system, and is set in the Warhammer 40,000 universe. Knowledge of the setting helps but is not necessary. Pre-generated characters are available.