Once a hero, always a hero... Having saved the Federation one more time in Star Trek: The Undiscovered Country, Captain James T. Kirk and the crew of the USS Enterprise have finally gone their separate ways. Spock, McCoy, Sulu and the others are spread out across the galaxy, pursuing their own individual destinies -- until an interstellar crisis touches all their lives.

Bored with retirement, Kirk jumps at the chance to help his nephews colonise a distant, uninhabited planet in a far corner of the Alpha Quadrant. He even persuades Scotty and Chekov to come along for the ride. But on the planet known as Sanctuary, colonists find they are not alone after all. An unknown alien race has established an outpost there for their own mysterious reasons. Suspicious, Kirk investigates, and uncovers a terrifying threat that strikes at the security of the entire Federation.