Greyson "Zero" King is a mob boss son. Though he doesn't want to take part of it, his dying father wants him to take over the Underground, their source of business where they organize MMA events. In order to prove himself, he was given a list of people and collect their debts in exchange for his mother's location whom he haven't seen for years. His life changed when he hooks up with the blonde girl who owned a blue Mustang. He's obsessed with her but when he sees her name on the list, the feeling of protectiveness for her prevails and he'll find a way to get out of it. 
 Melanie Dean is a decorator and Brooke Dumas's best friend. She's a carefree, hopeless romantic and selfless person. However, she has a debt after losing a bet in Underground. She's been warned by the mobs and asked for an extension while she saves up money. She goes to parties and looking for her prince charming. After the best intimate moment she had with Greyson, her instinct says he's the one. However, this enigma holds secrets and she wants to know them. What if his real persona will be the reason she needs to get away from him? Maybe he's not her Prince Charming but more of a villain. 
 Melanie and Greyson have a great chemistry and their intimate moments are steamy and sexy. However, I didn't like it became fillers and somwhat drag the story. I don't mind intimate moments as long as it still focuses on the actual conflict. Melanie annoys me on her spending habits. She has a debt to pay yet can afford to buy clothes, shoes etc.? I wish she saved earlier so she can pay her debts earlier. Greyson is sexy and intimidating but he's not my favorite. Though the mafia aspect is secondary in this book, I enjoyed the story despite of my issues with it. I like the drama near the end. 
 Final rating: 3.5 / 5 Stars