As the U.S.S. Cerritos crew has downtime during a long warp trip, a Klingon ship and a Vulcan one find themselves unknowingly heading to an encounter with the Starfleet ship.
Mariner finds herself held as the hoped-for ally of the disgraced Nick Locarno, now a megalomaniacal insurrectionist armed with a rebel fleet and a destructively planet-reforming Genesis device.