From the introduction:
When the ConFed has prisoners too valuable to execute and too dangerous to keep in the HighSec facilities coreward, they secure the criminals aboard the ships in the Maximum-Security Fleet. The longest serving in this capacity is the Tartarus, a hardened and upgraded version of the common heavy freight liner Niobe class. Exact specifications are closely guarded secrets and the location and itinerary are need-to-know only.
But word travels fast in your circles.
The Tartarus is late to rendezvous with sister ship the Erebus to transfer prisoners. And you have the coordinates of where it might be found. Can you act fast enough?