The Penthouse (The Rules Part Three) - The Penthouse, #3

Things between Ruby and Nick are heating up - in more ways than one. After agreeing to the rules of their steamy affair, they can't resist breaking a few of them. Before she knows it, Ruby is regularly sleeping over at his house and enjoying all-night-long hot sex sessions with her billionaire beau. But soon, the two of them are pushing risks further and further, beyond anything they had agreed to before.
And it will only be a matter of time before something - or someone - discovers the dirty little secret they've been trying to hide from the rest of the world...