Mining The Mind's Mines

The Cerritos and USS Carlsbad are sent to finalize peace relations between the Scrubble, who are rock-like aliens, and Federation scientists on Jengus IV. Mariner, Boimler, and Rutherford assist members of the Carlsbad crew in deactivating the Scrubble's psychic landmines, which tempt people with visions of their fantasies and then turn them to stone. On the Cerritos, Tendi starts senior science officer training under Dr. Migleemo who tasks her with getting the captain's attention during the peace negotiations. When several mines are accidentally broken they begin showing visions of nightmares. Fleeing into a nearby cave, the ensigns discover a lab where the Scrubble and scientists have been working together to gather Starfleet data. The Carlsbad crew also reveal that the Cerritos crew have earned a reputation as mavericks among the other California-class ships.

Summary from Wikipedia, CC BY-SA 4.0.