Review: SLIGHTLY SPOILERY.So, it’s the last in the Leviathan series. I loved the other two in the series, Leviathan and Behemoth. I reviewed Leviathan here before, but haven;t written a review of Behemoth yet. Maybe some day. Anyway, I was waiting for this book for ages, even though I knew it would be the end of the series and I’d be sad to see it go. So I was expecting a lot,We got a lot too. The Leviathan heads to Siberia, where they pick up Tesla, an inventor who says he can end the war. But no one knows whose side he’s on. so no-one knows what to do with him. Then they head on to Japan and America, meaning throughout the series, we’ve gone on a tour of half the countries somehow involved in WWI. In other news, Alek knows that Deryn is female and in love with him. All kinds of things could happen. And so the war and the crown of Austria and his heart all rest on Alek and his actions.Keith Thompson, as always, has blown me away with his drawings. My favourite one is the double page spread of Steampunk!Japan. it is recognisably Japan, but also recognisably different, if you get my drift. The other ones throughout the book are also amazing...I wonder if you can get prints...The action comes thick and fast. Something is always happening connected to some element of the main plot or other, and things that you instantly recognise from history/general knowledge that have been given their own steampunk twist just add a little extra something.I’m still in love with the characters. Deryn has always been the one I preferred between our two main characters, because I love the way she perserveres with everything, is awkward around Alek, and her own brand of profanity is so funny. the Russian guards also made me laugh a lot for some reason...The romance in this really suits it. It’s not often that I enjoy romance in a book that is clearly action orientated, but in this, I love it. I’d just like to say that I support Dr Barlow x Count Volger so much. I have done since book one, and I am so glad that it is implied heavily (at least I read it that way!) at the end. Alek and Deryn is the main couple for this series, which finally gets closure and completion in the most adorable way possible at the very end.Overall: Strength 5 tea to an amazing conclusion to the best steampunk YA series there is. Can’t wait for the Manual of Aeronautics, an art book released next year!