There are many reasons to join the Arcadius Fleet.
Grace Dillard joined to make her family proud.
Dean Lindsay joined to meet the family's expectations.
The fleet is currently traveling to an undisclosed location to draw a faceless enemy away from their home worlds. Communications are limited. Commitment to the mission is strong. Crews have been stretched thin to limit the likelihood of casualties.
And then a freak accident leaves Grace and Dean stranded, abandoned by the rest of the fleet. While they are waiting for a pickup they have the time to think about the questions they were never allowed to ask. That leads to them digging into some places they aren't supposed to go, where they find hints that things are not as they appeared.