Just battled Yarash, who appears to be in charge of this pyramid and the experiments on lizard men. Easy, easy battle, but I wish I'd had all my party healed up first. As I said, I'll probably replay this part.
Anyway, after the battle found some things in Yarash's desk.
Journal Entry 33 - Boss tells Yarash to join forces or die
Journal Entry 49 - unsent reply to the Boss's letter, rejecting offer to join forces
Journal Entry 27 - a message to buccaneers offering a 10000gp bounty for a real, recently dead sahuagin (?)
Journal Entry 56 - warning to an agent about the dangers in the mountains to the northwest (mentions a dragon!)
Journal Entry 40 - a note to a trapper about kobolds and hobgoblins (located to the east)
The letter to the Boss reveals that the Boss is in Valjevo Castle in the city of Phlan.
Also, there is a dial in this room which can be set to one of four different color settings. It is intially set to blue, but can be changed to copper, silver, or gold. I have no idea what this does.