although I would not recommend this book for someone who has just started with this universe I do recommend Into The Black Odyssey one series
Holy Ground gives a Back stories for both our main characters in The Odyssey 1 series King of Thieves spin-off series and the Angel One sequel series and I personally hope that this one has a continuation because there is a great deal to the early years that this book is the start of and just for reference from this point to the start of the Odyssey 1 series there seems to be an 8 year period and I for one would love to be parts of this roller coaster ride.
This is absolutely one of the funnest sci-fi universes that I have come across. and I hope there are others that will feel the same