Jeff That will be a very long summary considering there were four books before it. :) Why don't you visit wikipedia. If you are lucky, there might have plot summary of each book there.
This answer contains spoilers… (view spoiler)[I mean i could sum it up really quickly but spoiler warning if you haven't read it. So what happened before is that John Smith was introduced as our first Loric with his cepan friend Henri. Henri is trying his hardest to keep John alive while the mogs hunt them John discovers his legacies and the ability lumen. Meanwhile while this happened the mogs have managed to find him and are now going to paradise so to speak. Three humans found out about him Mark, Sarah, and Sam. Sam goes with them when they find six and then they go to find the others and thats pretty much it but sam gets capture and all that oh and they find a chimera named bernie kosar . and thats petty much it my man. (hide spoiler)]