Blackcoat by Steve McHugh

When Celine Moro took a job as a Blackcoat, an elite agency tasked with investigating crimes throughout Union space, she thought she had finally put her past to rest.

Now, betrayed by her allies, her world is falling apart. Running from the corrupt politicians that she had sworn to bring to justice, Celine is dusting off the skills of her old trade in order to bring truth to light.

The only thing bringing her comfort is knowing how much worse her friends are eventually going to feel about their betrayal.