The 4th? I wasn't aware there was even a 3rd. Oh well, I guess I missed the announcement.
I'm an avid reader and own the first two books, so I've have to look into this one.
The fact that it's related to Order 66 is interesting, since a lot of Republic Commando fans have been speculating as to what might happen if Order 66 was issued in Republic Commando 2.