She is not Invisible by Marcus Sedgwick
When Laureth gets an email saying that a man in New York has her dads notebook, she begins to get worried that he is missing. He hasn't texted her in days, and he's meant to be touring Europe, finding inspiration for his book. So she decides to kidnap her younger brother and take him on a journey across the Atlantic to find their father...
This is One Weird Book! I wasn't quite sure what to think about it. On one hand, it was a good idea, and I liked the characters. Especially Benjamin, Laureth's younger brother. On the other hand, I thought that the plot was on the slightly unlikely side. And I think that the fact that Micheal is 12 years old was totally uncalled for.
I am going to give it a 6/10
And an age rating of 11+