The Sharp Edge of Fate by TF Johnson

“It’s your job. You kill who I tell you, when I tell you.” The Belladonna is a shadow; an assassin who leaves purple-black berries on the bodies of her victims. No one knows her name, or her face. Piper is desperate to keep it that way. When an assignment goes spectacularly wrong, Piper’s carefully separated lives begin to converge. Her target becomes a reluctant ally as they search for clues to the disappearances haunting the city of Silversdale; disappearances that include Piper’s close friend, and a member of the empire’s ruling family. With two children in her care and time running out before she is due to deliver on her contract, Piper will soon find she has only scratched the surface of a plot that threatens everything she holds dear.