Question about Knights of the Blood

With the exception of one small 3 paragraph blurb in Nobelius Sanguinius and a few sparse mentions here and there in the Ventrue Clan Book, I can not find any information on this order but quite a few people keep telling me that there is a book out there with more details. Could someone give me a good direction to go in or at least let me know what books I need to be looking in?