Babylon 5 - Thirdspace

After being placed near the station the artifact begins to influence the dreams of many inhabitants of Babylon 5, eventually controlling many of them during their waking hours as well. These thralls, led by Deuce, first demand that the excavation be accelerated and then become increasingly violent towards the rest of the Babylon 5 population.

Eventually it is revealed by Lyta Alexander that the artifact is a Jumpgate that takes one neither to normal space nor to hyperspace but to a "third" space, built by the Vorlons a million years ago with a purpose that cannot be expressed in human language except as an attempt to make contact with the gods. In reality, thirdspace is inhabited by a violent race that posed a threat even to the Vorlons, and the ensuing battle ended with a group of Vorlons controlled by the thirdspace entities capturing the artifact and jettisoning it into hyperspace.

When the device is finally activated, the thirdspace aliens stream out and begin an assault on Babylon 5; the violent behaviour of the individuals under the artifact's control is intended to disrupt the station's attempt to defend itself. The struggle is ended when John Sheridan enters the artifact and detonates a nuclear bomb.