A side trip to an unknown star system, just to satisfy Petra's curiosity, ends well enough, but when they leave, they're caught up in a vortex of corrupted space and time. Managing to exit star drive space at the very last second, Jodi and Petra find themselves marooned, fifty light years away from the nearest star. Decades, possibly centuries away from anywhere, travelling at light sub light speeds.
Beside them is their probable destiny. A conglomeration of six starships, all intermingled across time, space, and multiple continuums. All caught up in an unresolved vortex, a state of being which Petra's FTL theories all say is utterly impossible.
Now they have to solve the impossible riddle, or sooner or later they're going to meet the end of the vortex , an explosion equivalent to a supernova eruption. And no one is likely to survive that.