The Enterprise is in hot pursuit of a Ferengi vessel, which has stolen a T-9 energy unit from an unmanned base. Both ships are passing through an unknown solar system, when suddenly both are rendered immobile and powerless. The Enterprise tries to exploit the .300 millisecond delay between force and counterforce, to no avail. The crew assumes the Ferengi have them right where they want them, but when they contact the Ferengi ship to discuss surrender, the Ferengi grudgingly surrender to them, believing that the Enterprise is responsible for their immobility.

Eventually, a probe finds that it's a force-field from the planet below that is responsible. The planet was once the outermost remnant of the long-dead Tkon empire, which was destroyed 600,000 years ago. Picard tells this to the Ferengi, and offers a joint expedition to discover what's going on. After much discussion, they agree.

However, the away team faces many problems. First, the force-field interfered with transport, separating them. Then, they discover the Ferengi beamed down first, and are ambushed by the Ferengi party. Yar rescues them and is about to stun the Ferengi, when the crystalline shapes all around them come alive and absorb the phaser fire (and the energy of the Ferengi whips as well). The "Portal" to the Tkon empire appears and demands to know why they have come. He has been sleeping for many hundreds of millenia and does not know of his Empire's collapse. He challenges Riker to take a test.

Riker passes said test (a test of wisdom), and Portal frees the Enterprise, just as reserve power is running out. Shortly after, he frees the Ferengi vessel, after Riker suggests mercy, saying that the Federation's moral code forces them to face even the possibility that they will one day be destroyed by a civilization such as this. The Ferengi return the converter, and both ships leave.