S1E25 · Conspiracy

Captain Picard receives a highly confidential message from Captain Walker Keel of the USS Horatio. Keel refuses to discuss his concerns and insists on a face-to-face meeting. At the meeting, Keel reports strange orders from Starfleet headquarters and what he implies are suspicious deaths of Starfleet officers and expresses concern of a conspiracy. After their meeting, the Enterprise finds that the Horatio has been destroyed. Picard has Lt. Commander Data review all orders issued by Starfleet Command in the past six months. Data finds several strange orders from the senior levels of Starfleet and Picard orders the Enterprise to Earth. As it approaches Earth, a transmission is received from a trio of Starfleet admirals, Savar, Aaron and Quinn. The admirals are surprised by the Enterprise ' s presence but invite Captain Picard and Commander Riker to dinner.

After witnessing the admirals' bizarre behavior and discussion of a "superior life form" Dr. Crusher discovers that a bug-like parasite has wrapped its tendrils around the stem of Quinn's brain and is controlling him. At dinner, it is revealed that the parasites are seeking to take over Starfleet, using humanoids as hosts. Riker and Picard subdue the infected men, causing parasites to leave the hosts and flee. One of the parasites scurries under a closed door, where Picard and Riker find Quinn's assistant Remmick eating the parasite. Remmick begins transmitting a signal.

Picard and Riker fire upon Remmick, destroying his body but freeing a giant parasite; the two continue to fire until it is destroyed. Dr. Crusher reports that the other parasites have shriveled up and died, as they were unable to survive without the mother-creature that had been inhabiting Remmick. Data theorizes that Remmick's signal was a homing beacon to more creatures like itself.