While the Enterprise is being repaired, a search is made for signatures that could match Orion activity, and it is discovered that the Orions are core mining a planet, presumably to provide dilithium crystals for the Klingons. The planet has a pretechnological indigenous population, so the Enterprise heads out to investigate. Captain Kirk leads the landing party, which includes Kell, down to the planet in System 7384, where they discover that the indigenous population is apparently a transplanted race of Klingons, and these Klingons are putting up a fairly effective resistance to the Orions. Kirk and his team join up with these indigenous Klingons, and attack the Orion base, but then they find that the warp core powering the mining activity has been set to self-destruct, which will destroy the planet. Meanwhile, the Enterprise has been called away to intercept a Klingon ship that has crossed into Federation space, the ship being the same one that Kell’s brother, Karel, is on. That ship is heading to collect the mined dilithium, and while the Enterprise does intercept them, the Klingon ship escapes after entering a red giant star. After two coups, Koloth becomes captain of the Klingon ship, and Karel becomes the bridge weapons officer. On the planet, the warp core is disabled, and the planet saved, but Kell reluctantly allows his roommate, Benitez, to fall to his death after he discovers that Kell is a Klingon. Meanwhile on Earth, another Klingon infiltrator kills herself after her attempt to kill Admiral Justman is thwarted by Ensign West.