You meet Jem on a bad day, he is shown a letter that makes him turn to the past to find answers. On the way you learn who he is, and how he ended up where he is. You meet past friends of his, all of whom were broken in different ways by the murder of one of their own. 
Are Jem's memories of his time at Oxford contain more fiction than fact? As Jem meets with his old friends he sees that they are just as followed by the past as he is. 
Uncovering who killed Toby requires uncovering all that was happening around Jem and the rest of the "Seven Wonders".
Well written, and hard to put down. Building Jem's past brings all the characters fully into being and the world really finds form in their memories and their present. At some points you feel bad for Jem, other times you can't decide if you should trust him, or his memory.
Are the Seven Wonders what he remembers? And how did it all come crashing down?