My Letter to Dan Brown [mild spoilers]

Dear Mr. Brown,
               I'm writing to you because I've finished your latest Robert Langdon adventure, Inferno. It was a well written book, with lots of interesting facts about Italian architecture and taut suspense.
               First, I'd like to talk about Dr. Sienna Brooks. I love the way you revealed her secret identity. First the unnamed traitor reminisces on a fond memory, leading you to believe that one character is the betrayor. Then, Sienna remembers that same memory. You've even written it with almost the same words. It was the best plot twist I've read in a long time, because it kept me guessing and suspecting all the characters of the book.
              Secondly, I'd like to commend you on your creative alliances. I started the book believing there were four teams, the first the Silver-Haired Woman, Robert and Sienna, the second the Consortium, the third group the people who had captured the Silver-Haired Woman, and the fourth group the person behind the plague that would reduce the world's population. As the book progresses, you meld each group with each other and split teams constantly, heightening the reader's suspicion with every character that isn't Robert Langdon himself.
              Finally, your conclusion to the novel was superb. The ending was really surprising but still made you feel like you should have seen it coming. The plague's purpose, Sienna's real identity, and why on earth everything is related to Dante's Divine Comedy, are all answered with apblomb. Best ending to a book I've read in a long, long time.
                                                                               Sincerely,
                                                                                       Tanvi Jagtap