Prison of Embers by Leigh Kelsey

They cuffed her. Branded her. Locked her up, and threw away the key. But Trouble won’t let these a*holes break her. Now a complete series! One teensy pyro accident, and now Trouble’s labelled an illegal dragon and sent to Blacktower, the secret supernatural prison beneath the Tower of London. Trouble doesn’t have a single memory of before the inferno, but the wardens don’t care—especially not the cruel Ravenmaster. Thrown into a cell block full of dangerous shifters and deadly magic, Trouble has one chance to reduce her life sentence: unleash her dragon so the Ravenmaster can clip her wings. But no matter how many towers he throws her from, no wings burst out of her back, and no horns grow from her head. The Ravenmaster thinks she’s stalling. But Trouble’s starting to suspect she’s not a dragon at all. And if she doesn't unravel the truth soon, she'll end up dead—or worse. Blacktower Prison for Supernaturals is a magical prison series, with a tough heroine and the sexy shifter mates who vow to keep her safe—not to mention the gravelly voice in Trouble’s head who knows her too well, and the darkly alluring Overseer determined to unearth her secrets. This book is medium burn, with moderate heat, and multiple love interests. 50,000 words.