Review:

Thomas Cresswell and Audrey Rose Wadsworth embark on a week-long voyage in RMS Etruria, heading towards New York. Their perilous adventures in Romania are over and they must accompany Dr Wadsworth to investigate a recent string of crimes. What not even Cresswell's amazing deduction skills can guess is that a crime-filled journey awaits them.
At the beginning of the journey, upper-class young women start to disappear and a series of brutal murders shock the ship's passengers. Suspicion soon falls onto the travelling Moonlight Carnival, aboard to entertain first-class members every night. Thomas and Audrey Rose investigate and try to discern which parts of the travelling carnival were lies and the truth lying underneath their ruses.
One thing I have to state right at the beginning of this review is that I believe that this is the book in this series which has the most complicated and complex murder plot. There is both a great number of details and few concrete conclusions throughout the investigation of these new murders. At times it feels like Cresswell and Wadsworth are grasping for straws but in the end, there is the shocking revelation of the killer's identity and I would have never guessed who it was.
Many things make this book amazing and one of them is its characters. Audrey and Thomas we already know, still we learn a lot about them and their dynamic throughout the events of this book. There is also more development regarding Liza, Audrey Rose's cousin and the introduction of a whole new "main supporting character" (as I like to call it), Mephistopheles. Mephistopheles, or Devil, as Thomas likes to call him, is, in a way, a Cresswell-like character that represents the first-ever romantic opponent Thomas encounters in his relationship with Audrey Rose. I could write many paragraphs about Mephistopheles but I believe that would spoil much of his character. The best way to describe him, in my opinion, is if Thomas was arguing with himself in the mirror, but that other self had a mask on his face and sequins in his clothes. Obviously, the title character, Harry Houdini, makes his appearance, although he does not have a very preponderant role in the plot.
I love the way Thomas acts towards Audrey: he never limits her choices, even when they may (and do) hurt him. To me, Mephistopheles has the great role of being a catalyst in Audrey Rose's exploration of herself and the world around her. In this book she gets a bit distant from Thomas in order to explore things on her own and, even though it hurts my heart, I believe it is beneficial for both of them. Thomas' personality also keeps evolving, he not only lets himself feel but is not afraid to show his feeling (which made this book a lot harder to actually read). There are some Thomas and Audrey alone moments where you can just feel the electricity in the air and how their attraction towards one another muffles their logic. These are tender, witty, electric and lovely moments that I loved to read.
The Carnival aspect of this book makes a lot of sense, and it was well incorporated in the murders. There is a touch of showmanship in everything that happens. Some trade secrets are dispelled as Audrey Rose unveils the artist's secrets but there are hidden truths that remain, even when the story is over. Also, I loved the blasé reference to P. T. Barnum, if you watched the movie "The Greatest Showman", yes the one with Hugh Jackman, you will know whom I am talking about.  Also, that same movie kept jumping into my thoughts as I read this story and I loved it!
As with the rest of the series, I loved this book and cannot wait to see what happens next! (And I impulse bought the next instalment too so a review may not be very far ahead!)