“Babylon 5: The Gathering” is the feature-length pilot episode of Babylon 5, although it is not chronologically the first in the series; that being “In The Beginning”, which was filmed later.
The episode opens with a narration about how it is the dawn of the Third Age of mankind, the year 2257, with the founding of the last of the Babylon stations, deep in neutral space, and how the narrator was there. A port of call for all kinds of people and races, it is sometimes a dangerous place, but the last, best hope for peace. This peace has been put at risk by the arrival Del Varner.
The station’s commander is Jeffrey Sinclair, and he is contacted by security chief Michael Garibaldi; there is a new arrival who needs Sinclair’s personal clearance to come aboard. This arrival is Lyta Alexander, a telepath from Earth Central. Babylon 5 is effectively a free port, and only Earth Alliance is allowed to have arms on board. Sinclair escorts Alexander to her quarters through the alien sector (the aliens oddly appear to be on display) and, at the end, she asks why this is Babylon 5. The first three Babylon stations were sabotaged and destroyed; the fourth vanished 24 hours after it became operational and hasn’t been seen since. Not exactly reassuring. The station itself appears to still have some final finishing touches being done to it.
There are currently ambassadors of three of the four main alien races (there are four more) are already on board; Kosh, the ambassador for the fourth race, the Vorlon Empire, is expected in two days. The Vorlons have never been seen in person and are a mysterious race. The other ambassadors are Delenn of the Minbari Federation, G’kar of the Narn Regime and Londo Mollari of the Centauri Republic. Delenn, despite it only being ten years since the Minbari and the Earth Alliance were at war, offers Commander Sinclair all of the information that her people have on the Vorlons. Which isn’t a great deal, but it’s more than Earth Central has.
Kosh arrives two days ahead of schedule and departs his craft in an environment suit. When the welcoming party enters the area where Kosh is, he is lying on the floor, apparently unconscious. The secretive Vorlons don’t want anyone to help Kosh but Sinclair says he isn’t having an ambassador die minutes after arriving on the station, and asks Dr. Benjamin Kyle to treat him.
Things get worse when it’s discovered that Kosh didn’t just collapse from natural causes, but is the victim of an attack. The problem is, who carried out the attack and why? Kosh is not dead yet, but he is dying, and unless more is discovered, and soon, things could go badly.
Events may trigger a war between the Earth Alliance and the Vorlon Empire, and when evidence appears to suggest that Sinclair is the one responsible, things get even further out of hand. Someone may be trying to provoke a war but, if so, why? Clearly, more is going on, but this is only the first episode, so more is yet to be revealed. The opening episode shows some of the relationships between the five major polities; they are not wonderful, and look like they could go badly wrong in the future. Oddly, the Minbari ambassador, Delenn, and Sinclair seem to get along well, yet they represent the two polities who have most recently been at war.