This is the 7th episode of the first season of Star Trek the Next Generation, written by D. C. Fontana, of considerable ST:OS fame, and Michael Halperin. The USS Enterprise is transporting representatives from two warring worlds, the Selay, and the Antican, to treat on the neutral world of Parliament. The basic premise is very similar to that of the original series episode "Journey To Babel," but alas, even with Stewart's skill, this episode suffers in that it lacks a character like Sarek, and an actor like Mark Lenard. It's also got that hoary original series device, an "energy cloud," which turns out to be sentient with a predilection for possessing corporal bodies, first that of Worf, and then Dr. Crusher, who both exhibit odd behavior and memory lapses. From Dr. Crusher, the "energy cloud" moves to the computer systems of the Enterprise. Picard orders an investigation, and the red shirt engineer assigned to the task later turns up dead—launching a murder investigation, and placing the delegates and their entourages under suspicion. Eventually, the energy possesses Picard, begins to be mysteriously incommunicative, and orders the ship to drop out of warp, and return to the cloud, despite the consternation of his senior officers. Picard beams himself out to the cloud, but then manages to signal the ship. Geordi La Forge figures out how "reconstitute" Picard's pattern using the transporter, but leaving behind the entity. And yes, I'm skipping lots and lots.
This is one of those rather heavily didactic episodes, and, given that Roddenberry also credited with the writing along with Fontana and Halperin, I suspect Roddenberry's influence. He was rather fond of binary oppositions, even to the point of reductio ad absurdum. First, the introduction of the Selay and the Antican is such that viewers are encouraged to view them as barbaric, and even bestial—aided and abetted by the words of Picard and Yar. This is just bad SF; it's the alien-as-other-let's-kill-the-freaks, and well, that's a little too close to modern history to work.
We see Colm Meaney, later (season 2) to be known as Transporter Chief O'Brien in this episode, as a security guard, and honestly, he really does sorta stand out. We also see an early version of what was to become the standard TNG issue PADD, long before Apple's iPad appeared, but damn, I guess I know what Jonathan Ives likes to watch. We see the first instance here of Data glomming onto a fictive idea; here Sherlock Holmes, and running with it, right down to the deerstalker and pipe, thanks to an off-hand remark from Picard; this is the Data-as-light-relief motif we saw in "The Last Outpost" with the Chinese finger-trap, and it already sucks. I note, along with Wil Wheaton, that the dialog and characterization created by writers who should know better (Like D. C. Fontana) for Wesley Crusher is embarrassingly awful. I don't know how Wheaton managed to cope. I think, honestly, that we see both Wheaton and Brent Spiner as Data saving lazy writers.
The official trailer for "Lonely Among Us"
The previous episode was "Where No One Has Gone Before"; the next episode is "Justice."

