From the synopsis:
The Players go undercover on the pre-contact planet Kalmur to investigate the apparent death of a Federation observation team member. That team has been observing a Kalmuri experiment in artificial gravity, potentially leading to warp drive within decades. But the experimental gravity generator ran wild and crushed everyone in the lab, including a Starfleet scientist, Lieutenant Li, who’d infiltrated the project as an observer.
While investigating, the crew is confronted by a Kalmuri detective, Lanox, who’s convinced the deaths are the result of sabotage. But the sabotage could only have been performed from within the lab while the generator was running, and no one could have gotten out alive in time. Lanox has deduced that Li was an alien in disguise and recognizes the crew as more aliens, suspecting that they may have used advanced technology to commit the impossible locked-room murder. She says that if they want to convince her of their innocence, they must help her solve the case using their advanced knowledge.
Aiding in the investigation could violate the Prime Directive – but the crew’s preliminary scans of the remains reveal a dearth of human DNA, suggesting that Li may be alive, possibly a captive of the killer. They must investigate in order to find him.