Tommy peruses the book for a while, flipping through the maps and sketches. He has seen plenty of prints in the Academy's library, but those collected in this book are just all over the place. Notably, he recognizes the grid like maps to be sewer systems, some of the sketches are probably caves or cave networks. Also documented are mansions, a couple of towers (though none that are Thyrin's floorplan), and one massive public building, probably a court house. Tommy knows that Fallon must have an impressive water works to deal with the constant influx of water, but he has no idea what it looks like.
The shovel does not seem magical, though it is obviously well designed.
Keldar remembers that a huge network of sewer tunnels remains beneath Orussus from the creatures that originally built the city. But a quick glance from Tommy shows that the maps in the book are on too small of a scale to accommodate minotaurs, if the blueprint measurements are accurate.
You bring the book and shovel to the front door. Cassandra appears almost instantly. The book elevates out of Tommy's hands and hovers in the air before her. Pages flip before her eyes, and she hmmm...'s "Now this is quite a find. Look at these pages:" The book spins around and reveals some of the professional blueprints. These are of a five story tower, of similar diameter and shape to Thyrin's tower, but the floor layouts are completely different, and there's not a furnace. Of note, there is an additional floor beneath the first: a basement, as it were.
Cassandra chuckles and says, "Perhaps his wariness is not so misplaced as I thought. Come on, let's go talk to him." She brings you all upstairs to the library, where Thyrin is writing at his desk. You show him the book and the shovel, Cassandra mentions the pages she showed you all.
"Aha! You see, I told you that fellow was a scoundrel! Ah, you all are unaware of course. When I first built my tower, I commissioned a Fallonese architect living in Orussus to draw up the plans. He was a likable fellow, and supposedly had experience in designing some of the public buildings in Fallon, but something didn't smell right about him. I paid him and sat on the plans for a while, and then decided to scrap them and make my own plans. Took a lot of research, but I got it together, and even put a furnace on the second floor. I didn't feel confident enough to build a basement, however, so I just filled in a big foundation. Stone is cheap when you have living earth on your staff." He turns to Cassandra. "She thinks I'm crazy for having tossed those expensive blueprints, but I am vindicated! So they thought they could break into my tower through the basement... Ha!"
"These other prints, though, they don't ring a bell... Some of them look like sewer systems, though I certainly couldn't say which city. Doesn't Orussus have a sewer system? As for this, it is a rather odd shovel. I can't say I know anything about that either. There is a spell... it gleans information about obscure items, but it is beyond my abilities. Beyond the abilities of any wizard I have had the pleasure of meeting, actually. I've only read about it in books. But... perhaps a bard might be able to help! Grenton is rather short on bards, but I know of at least one famous fellow in Orussus. Val- eh... Valley Doll, or some such." Thyrin taps his chin for a moment.
"Tell you what. You folks find out about these bandits for me, and I'll compensate you for your trouble. No need to bring anybody to justice or anything, I'd just like to know who's after me and why. Will you do that for me?"