Nothing to Hide by James Oswald

Overview: Suspended from duty after her last case ended in the high-profile arrest of one of Britain's wealthiest men, DC Constance Fairchild is trying to stay away from the limelight. Fate has other ideas . . .
Coming home to her London flat, Constance stumbles across a young man, bloodied, mutilated and barely alive. She calls it in and is quickly thrown into the middle of a nationwide investigation . . . It seems that the victim is just the latest in a string of similar ritualistic attacks.
No matter that she is off-duty, no matter that there are those in the Met who would gladly see the back of her, Con can't shake her innate determination to bring the monsters responsible for this brutality to justice.
Trouble always seems to find her, and even if she has nothing to hide, perhaps she has everything to lose.