I've loved Ally Carter's novels for a while now and particularly favour the Heist Society books. They're the definition of perfect!I read Uncommon Criminals back in November and loved it. Since then I have been waiting patiently to read this (okay, maybe not so patiently!) and when I read the summary, I knew the wait would be so much harder.In this novel we see Kat and Hale's characters develop a lot more than in the previous two novels. Kat is facing her hardest job yet and the stakes are high. Failing means losing one of her best friends and it is not an option.These books are written in a much more sophisticated style than the Gallagher Girls novels and are clearly aimed at an older audience. I particularly love the descriptions of the time and setting at the start of certain chapters. This is something that I would like to see more of and is also something that I have always liked.Kat is under so much pressure in this novel and it was nice to see a realistic side to her. The change was evident and I actually preferred this new Kat.Hale! Woah! His part in this novel was huge and it was so nice to see his character development.There are a lot of familiar faces in this novel: Gabrielle, Simon and the Bagshaws. Gabrielle was just as kick-ass as usual and I love her character so much.The Bagshaws never fail to make me laugh; they're just so funny!One of the best things about these books are the covers. In this one we can see Hale reflected in one of the lenses and the model who plays Kat has stayed the same for all three books. They are instantly recognisable as the Heist Society books.I read Perfect Scoundrels within a day and it is certainly my favourite of the three novels written so far. It is thrilling, humorous and completely unique.