Pariah

This novel by Dan Abnett is the first of his third Inquisitor trilogies (see Eisenhorn and Ravenor for the other two), and follows Alizebeth Bequin, a youth at an orphanage school in a strange but relatively (for the 41st millennium, anyway) peaceful city. She has grown up being trained in a variety of esoteric and espionage-ish arts, and is rather good at what she does. But then a job goes slightly sideways, and her whole life is thrown out of balance - new people come into her periphery just as old ones are violently ripped from it, and she must do whatever she can to keep her head... I'm reluctant to say more than that because of spoilers for the previous pair of trilogies. But as ever with Abnett, the writing is as fluid as it is punchy, the characters feel lived-in and believable, the action is - well, full of surprises; and the overall interpretation of the world of Warhammer 40,000 is magnificent in scope and thoroughly original despite never deviating from the essentials of the lore.