|As soon as you reach 5th level and try to fast travel, you'll get an invitation from Prince Lhotun asking you to come visit him at Sentinel. Once in a great while there is actually a courier, but usually the letter just appears in your inventory.|
|Prince Lhotun is the young fellow sitting on the floor to the right as you go up the ramp from the entrance of Castle Sentinel. He's a nice enough guy and has information you probably want ("definitely want" if you're going to complete the Main Quest). But, like every one else you talk to, it's a quid pro quo situation. You've got to do something for him before he'll give you the information.|
Lhotun wants to know what happened to his older brother. Ask about him around town to find out that he was a scholar, died several years ago, drove the King crazy because he didn't want to play with swords, and that the king was awfully happy when he died. After you ask enough people (good practice on that Streetwise skill) and have waited long enough, you'll get a letter from an agent of the Underking. The letter will arrive several days later (anywhere from 10 days to 2 weeks) and will tell you to investigate a certain dungeon for information about the missing prince.
While you're waiting for the letter, talk to people, sit in your inn and cast spells, steal the armor shops blind (there are four of them - two of them extremely high quality) or whatever. The dungeon is supposed to be random, as is the location of the letter you're looking for, but once you find it (and read it), you'll discover that the Royal Parents in Sentinel aren't as nice as they would have you believe. (Is it just me or are dysfunctional families the rule for royalty?)
After bringing the letter back to Lhotun, he'll tell you what he knows about Lysandus. Specifically, that Lysandus was hot to trot for a certain royal sorceress, Medora Direnni, and wasn't entirely discreet about it. And who says this game isn't like real life? Lhotun will also mark Direnni Tower on your map (it's on the big island in Balfiera) and give you something for your troubles. All in all he's the nicest NPC you'll have to deal with, so enjoy it while it lasts.