Court of Darkness by C.N. Crawford

I would not say things are going well, exactly. I live in a burnt-out car under a bridge, surrounded by rubbish. When Ruadan shows up to bring me back to the Institute, I leap at the chance.

That is, until he throws me into the dungeons. I’m on the naughty list, and the mentor who once trained me is cold as ice. Now, I must pass every single trial, or the Institute’s executioners will rip me to pieces. Good thing I can handle it. I was the queen of the gladiator ring, and I do not go down easily.

This book is from the Demons of Fire and Night world.