"Hellfire" is Ia's doomsday ship - and the members of her handpicked crew are Ia's Damned.
Hellfire and the Damned run around the galaxy picking off the bad guys and working to set up the sequences of events that will save the galaxy three hundred years in the future.
We have known for some time that Ia and her half-twin brother (different mothers/same father) are the children of a member of an energy-based species that can operate on the physical plane if necessary and whose primary purpose is to interfere in the workings of the universe of physical beings. Hence, they are generally known as "Meddlers." This is their great "game." What we haven't known until this story is that half-breeds like Ia can sometimes actual become members of the club.
I was warned that I wouldn't like the ending - and I didn't - for the usual reason. There is no conclusion; everything is just left hanging for the next book in the series. Always annoying - but not so annoying that I won't read the next one - as sometimes has happened.