Cassel knows he's being used as an assassin, but he's trying to put that behind him, trying to be good, trying to do the right thing. It isn't always easy when your family is full of con artists and the girl you love is a mobster's daughter. But the line between what's right and what's wrong becomes increasingly blurred. When he's asked to do the one thing he'd never do again, he needs to sort out what's a lie and what's truth, and whether or not he'll make the biggest gamble of his life.Black Heart was exactly what I was looking forward to reading, it was still dripping with noir, reminding me of the 1920's and its gangsters. And, like with the previous two books, so many different shades of good and evil, of cons and truth. There's the truth we know, but then there's the truth as Cassel knows it, the truth with different shades of grey. Fresh off making a deal with the FBI, Cassel still in deep, but what trouble is it this time? Can he work himself out of it?One of the best parts of this series is Cassel himself. From a family of curse workers and con artists, he's the only good guy with an honest heart. He's always working himself out of the hole that his family and other circumstances dig deeper around him. There's so much he has to juggle, so many truths and lies, so many things he can and can't say to certain people because of those other circumstances. He may look like one of the bad guys, but when everyone else is worse, is even more dangerous, then Cassel's definitely one of the good guys.It often feels like Cassel's the one who's trying to stay straight, a few cons here and there, maybe a little gambling in the dorms, while the rest of his family pulls him down. His brother's no angel, and it seems that his mother isn't happy unless she's conning some rich guy out of his money so she can keep living the high life. Then there are the agents who want to keep him close, who want to use him, who want him to take of his gloves.Lila. Cassel's still in love with Lila, as he should be. There's no one else for him, only this daughter of a mobster will do, this daughter that's joined the family business. And Lila's still in love with him, but the situation becomes ever sticker, and, like every book in this series, there's never a guarantee that they'll end up together. Or that Cassel will survive until the end.Cassel's unpredictability coupled with his good-guy attitude kept me guessing right until the end of the book. I couldn't expect anything good or bad, I could only rely on Holly Black to take me wherever Cassel went. All that was left for me was to hope he didn't get betrayed, hurt, or killed. Or all three.