Open If You Dare — Dana Middleton

Like Birdie Adams didn't have enough problems this summer. But Birdie's Birdie. And if a long-buried box has "Open if you dare" written on its lid, then Birdie and her best friends, Ally and Rose, are going to open it.

And now, along with everything else that's going on--Ally's pitching slump, Rose's banishment to Britain, and Birdie's annoying younger sister being, you know, annoying--the best friends are caught up in solving a mystery planted by a dead girl forty years ago.