The year is 2300, and seven years have passed since the events of the film Star Trek VI: The Undiscovered Country. A space station orbiting the Klingon colony Da'Kel is being used as a staging area to undo the disastrous fallout from the destruction of Praxis. With the help of aid supplies from the United Federation of Planets, reconstruction is in progress - but the peace process begun by the Khitomer Accords is still fragile. Unknown to either the Federation or Klingon representatives warily watching one another over Da'Kel's skies, a third group is plotting.

Unnoticed by security, a civilian transport ship with a skeleton crew docks at the station. The ship transmits an ancient Klingon proverb - Traitors cast no shadow - before destroying itself in a massive blast of subspace energy that obliterates the space station.

Meanwhile, light years away in a Starfleet penal complex, former officer Valeris is in counselling with her Betazoid therapist. But the process is proving difficult, as Valeris refuses to let down her defenses. She has little hope of ever regaining her freedom or returning to her native Vulcan; guilty of murder and treason against the Federation, she believes she will never be able to go home again. An observer has also been watching - none other than Spock himself, recently retired from Starfleet service and now a representative of the Federation Diplomatic Corps. Spock has come to Jaros II to see Valeris because he believes he is to blame for failing to prevent her attack. He is as marked by that incident as Valeris, carrying the guilt of what he was forced to do....