Ensigns disarming psychic mines on Jengus IV stumble onto a hidden lab and a spy device.
The Cerritos and the USS Carlsbad are sent to finalize peace between the rock-like Scrubble and Federation scientists on Jengus IV. Mariner, Boimler and Rutherford help the Carlsbad crew disarm Scrubble psychic mines, which show their victims fantasies before turning them to stone, and when several mines break the crew is hit with nightmares instead.
Fleeing into a cave, the ensigns discover a lab where Scrubble and scientists have been collecting Starfleet data. On the ship, Tendi begins training to become a senior science officer under Dr. Migleemo, and she discovers that a gift given to Freeman and Captain Maier of the Carlsbad contains spying equipment.