Earth is being conquered by the Centaurs in multiple timelines, some of Valentinian's crew have already been lost, and the Sapphirus Tempus has been destroyed. The Centaurs' human-like androids have infiltrated human society in each timeline, and their simultaneous attacks across the world precede each incursion with devastating effect, allowing the Centaurs to invade during the chaos with little resistance.
Divided across centuries of history with no way to get back to their ship, William and his crew are determined to do whatever they can, despite the futility against such a force, to impede the Centaur invasions of their respective time zones while facing such dangers as the sinking of theTitanic and the French Revolution. But unless they can find a way to reach each other across the fractures of time they will not be able to escape sharing humanity's fate.
