Mutant Mine by Venus Nox

The Hades is on its way across the stars, transporting condemned men to the mining planet Chronus.

Prison ships only accept male crew — but Rory Finch isn’t going to let that stop her. So she puts on a chest binder, cuts her hair, and disguises herself as a boy. All she needs to do is get through one journey, then she can collect a sweet paycheck and get the hell out of there.
Locked down in maximum security is a prisoner like no other: Roth. With his swirls of reptilian skin, freakish size, and the twisted horns that crown his head, even the worst of the worst fear him.
Guarding Roth’s cell, Rory can feel his eyes on her all the time. There’s no way he could know her secret… right?
He’s terrifying enough when he’s confined. But then the engines fail, the power cuts out, and the force-fields drop.
Now he’s free. And he’s coming after her.