Investigating a series of violent raids by a mysterious predatory species, Captain James T. Kirk discovers that these events share a startling connection with the First Federation, a friendly but secretive civilization contacted early in the USS Enterprise's five-year mission. Traveling to the First Federation in search of answers, the Enterprise suddenly comes under attack from these strange marauders. Seeking refuge, the starship finds its way to the true home of the First Federation, an astonishing collection of worlds hidden from the galaxy beyond. The inhabitants of this isolated realm are wary of outsiders, and some accuse Kirk and his crew for bringing the wrath of their ancient enemy down upon them. When an attempt to stave off disaster goes tragically wrong, Kirk is held fully accountable, and Commander Spock learns there are even deeper forces that threaten this civilization. If Kirk and Spock cannot convince the First Federation's leaders to overcome their fears, the resulting catastrophe could doom them all!