I am doing the mission called Life of the Party where I move through City Rooftops into a 6 floor mansion where I have to find a schematic, listen to audio recordings of this Karras.

I am however stuck on this one mission objective listed as this:
"Find and read Karras' latest entry into the New Scripture of the Master Builder."

I looked everywhere and I cannot find this latest entry. The weird thing is I already have a Scripture Passage but I cannot find the others anywhere. I explored almost every nook and crany in the mansion.

So anyone can give me a hand here?

http://www.thief-thecircle.com/guides/keeperchapel/Party/
http://www.thief-thecircle.com/guides/keeperchapel/Party/secrets.asp
http://www.thief-thecircle.com/guides/keeperchapel/Party/lootmap.asp

Edit: I'm pretty sure it's on the 5th floor, in a safe in a room that has that small golden child?

How was I supposed to know I was supposed to lockpick it? It looked like the kind of thing that you needed to flip a switch for to open it.

Riiiight, spoken like a true master thief, riiiiight...