Pubblicato in Italia con in titolo La gemella sconosciuta. Callie e Tilda sono gemelle, ma non potrebbero essere più diverse. Mentre Callie è introversa e con zero vita sociale, Tilda è piena di vita e un’attrice sull’orlo del successo. Nonostante le loro diversità, Callie e Tilda sono molto legate, finché Felix non entra nelle loro vite.

Callie and Tilda are twins but they are completely different. Growing up, Callie was the shy and more reserved one, with her face always inside a book, and Tilda was the popular girl in school, full of friends, and interested only in clothes and make-up. Now adults, things haven’t changed much, Tilda is an actress, while Callie works in a bookstore and doesn’t have much of a social life besides movie night with her sister. One night, Callie goes to her sister’s flat for one of their usual movie nights, but she is surprise to find out that it is going to be just the two of them as Tilda has invited Felix, her new boyfriend. Although at the beginning Callie is charmed by Felix, soon she starts to notice how controlling and obsessive he is and she suspects that her sister is in an abusive relationship. Unfortunately, there is little Callie can do because Tilda is in love with Felix and soon they are living together and getting married. Still worried, Callie joins an online group for families of victims of abuse and from there things get out of control.

If you are looking for a fast-paced thriller, then this is not the right book for you. In this novel the action is very slow-paced as the author focuses mostly on the complex psychologies of all the characters involved. I loved how the author explores in depth their fears, their secrets, their hopes, and their obsessions. Especially their obsessions because it seems that every character in the novel as its own (good or bad) obsession.

From the first page, the author informs you that something really bad happened and as you keep reading the tension is high, but the surprise and twisty ending is really unexpected and you really don’t see it coming. A remarkable and captivating psychological thriller that you won’t be able to put down until the word ‘end’!