Starfleet Task Group Eurus-7 vanished over two centuries ago, venturing into what is now Klingon territory and never being seen again. In the aeons that followed, through intelligence and diplomacy, slivers of the truth have slunk out: a confrontation with the Klingon Defence Force, a battle lost, the Starfleet ships and crews among the earliest casualties in the long and fraught history of Federation-Klingon relations. Even as the relationship has warmed, however, local Klingon houses have guarded their territories, histories, and secrets jealously, leaving the fate of Eurus-7 a mystery.

The fall of the local ruling Klingon house is, for the Federation, a point of concern – a disruption of the delicate balance, a question of how the warmongering Chancellor Toral will reassign territory, reassert control. Until then, a situation that admirals describe as a political concern is nothing but an opportunity for enterprising Captain Evelyn Pentecost of the USS Tempest. An explorer and historian, Eurus-7 is a mystery that has long captured her imagination. If ever a Starfleet ship could venture into the Skaleri sector and discover her fate, now is the time window, before any single Klingon House can declare itself the region’s new master, and, perhaps, bar the doors anew.

But Tempest may not be alone in coming for this mystery, and history will side with whoever controls the story.