My 15yo got this at the library, and really liked it, so I thought I'd read it.
What happened to Milly last summer? She can't talk about it. Instead, she's writing in her journal. About growing up in the shadow of her twin sister, Lily. About the American boy who's moved in upstairs. (There's something he's not telling either.)
Milly can't keep her secret forever . . . can she?
So, this one really cute. My youngest daughter is a typical 15yo in a lot of ways, but she is not a huge fan of YA books, and most of them don't really speak to her, so her finding something that did was a treat.
I found it a little predictable (I realised what "The Incident" as it is mostly referred to, must have been, pretty much immediately), but that didn't hurt it. In fact I really liked the last few chapters, after the big reveal.
The heroine here is very close in age to my daughter, she turns 15 at the end of the book. There's a budding romance, but it's very sweet and gentle, and "the boy" doesn't immediately become the center of Milly's world. And there's a best friend who really is a best friend: Effy is a fabulous character, supportive and kind and practical, any girl would love someone like her on their side. All the characters are well drawn in fact, even the mean girl at school is realistically nasty, rather than totally over the top.
I'd personally rate this a 3 but then I'm not really the target audience. Daughter gave it a solid 4, so I'm splitting the difference. If you have kids in the right age range (I'm going to guess, 13-15 would be the sweet spot), this might be worth a look.