Plot summary
Diverted from exploring the Pleiades, the Enterprise arrives at the terraforming colony on Velara III, as the project is behind schedule. The director, Kurt Mandl (Walter Gotell), insists they are on time but Captain Jean-Luc Picard (Patrick Stewart) orders an away team to the surface after Counselor Deanna Troi (Marina Sirtis) senses that Mandl is hiding something. After they arrive, one of Mandl's team is killed by a malfunctioning laser drill. During Lt. Commander Data 's (Brent Spiner) inspection of the tool, it begins to fire at him, but his quick android reflexes allow him to dodge the shot and render the drill harmless. He discovers that the laser had been reprogrammed to fire upon the staff. Nearby, a crystal is discovered giving off irregular light and radiation patterns. The crystal is brought aboard the Enterprise to study and Picard orders a halt to the terraforming.
Dr. Beverly Crusher (Gates McFadden) and Data discover the crystal may be alive. When the crystal attempts to interact with the Enterprise ' s computers, it is placed into a containment force field. The crystal begins to grow and gains access to the computer's translation program and attempts to communicate with the crew, treating the humans as an enemy, derisively calling them "ugly giant bags of mostly water". Picard discovers that Mandl and his team previously encountered the crystals; at the time, they had considered the possibility that the crystals were alive, but Mandl insisted on continuing to terraform.
The terraformers used a drilling process responsible for removing the saline water layer from the water table of Velara III. This saline layer acted as a conductor, allowing many separate crystals to function as one life form. In a defensive response to the drilling, the crystal life form rewrote the laser's software and attacked the terraformers.
Dr. Crusher hypothesizes that a single crystal is not intelligent, but when linked to other crystals, their intelligence is formidable. As the crystalline life form accesses higher-level functions of the Enterprise ' s computer, Picard and the crew try to transport it to the surface but the crystal blocks all attempts to transport it off the ship. Data and Lt. Geordi La Forge (LeVar Burton) discover the presence of cadmium in the crystal and suspect it has photoelectric properties. They disable the lights in the medical lab and the crystal immediately begs for life. Picard peacefully negotiates to return the crystal life form to the surface of the planet where Starfleet will institute a quarantine, leaving the life form to live in peace.
Credits
Adapted from Wikipedia contributors, Home Soil. Paragraphs and formatting adjusted; illustrations, reference markers, block quotations and non-story material omitted.