"Necros" was the Federation's classified name for the world. The planet hosted a Klingon base defended by a variety of interplanetary missile batteries. Two moons, or possibly two other planets in its star system, could be seen from orbit.
In 2265, the mutinied crew of the Federation guardship Dorado fled for sanctuary within the Klingon Empire. After Klingons on Scaptar attempted to kill the crew, mutineer leader Erhard Voss responded by assaulting Necros, thinking that Klingons respected strength and that his actions would lead to a barter for political asylum. However, James T. Kirk feared that this attack could incite a Federation-Klingon war. From aboard the USS Enterprise in Federation space, Spock was able to divert the guardship away from Necros. (TOS comic: "Mutiny on the Dorado")