Actual rating: 4.5/5 stars 
 I gotta say this is my least favourite book in the trilogy. It was probably because I had high hopes of it. I was expecting it to be more of an epic battle and more action-packed tbh. But overall it was still SO good. Claudia Gray never cease to amaze me with all the concept of dimensional travelling and of endless possibilities. 
 I enjoyed this thoroughly. I love Marguerite even more in this book as she has become more matured and she thinks before she acts which I really appreciate. Paul is still as charming as ever. Though he never quite showed his affection towards Marguerite, I understand he was being careful. Theo Beck. Oh how do I start with him? I absolutely love him. I've always loved him from the very first. I thought that he deserved much better. His brotherly relationship with Paul is none other than anything in the world. It's everything. The way he calls Paul "Little Brother" gets me everytime. 
 I also like how the romance was really subtle and not overdone. Thank you, Claudia Gray for that. 
 The last few chapters were my absolute favourite, when they all come together as a team and it just shows how Marguerite, her parents, Theo and Paul has always been a great team together and it kinda makes me somewhat emotional. 
 Overall, I gotta say this trilogy changed me in so many ways and will totally be in one of my favourites trilogy ever. It is also the first book that made me realize how I love science fiction and how I really like science and its impact towards life.