Three years have passed since the events of the previous New Frontiernovel, Missing in Action, and tensions within the New Thallonian Protectorate are at fever pitch following the murder of Prime Minister Si Cwan. Captain Mackenzie Calhoun and the crew of the USS Excaliburface an uncertain future in the turbulent Andromeda Galaxy. The sudden power vacuum will have far-reaching consequences for them all, as lives and the very fate of Sector 221-G are catapulted into utter chaos.

In Treason, the New Frontierstoryline jumps ahead three years from the events depicted in Stone and Anvil, picking up again at a point of crucial change, where new and old Star Trekreaders are at the same level of discovery for the series.