Thanks for joining, Rascal.
I'm thinking at the moment that Retief just gets himself into more and more trouble. I notice that Derwyn is also experiencing some culture shock in this new city, though obviously in different ways to Retief.
I'm thinking both Derwyn and Retief could get dragged into some deeper secret the city holds. I'm imagining there are some wealthy vermin in the city involved in black market trading, and Retief could discover that his brother has become involved with them.
Perhaps we could also tie that into Rioko's plan to break into a manor to steal a necklace? Let's say there's a fancy party planned at the manor that night. Retief learns that his brother is attending the party, and tries to find him, only to get further pulled down the rabbit hole. Perhaps the necklace is in fact part of the black market plot? It's being exchanged in secret at that party tonight between the owner of the manor and a guest as payment for some illegal goods, or slaves.
I'm imagining something like a fancy dress party with masks, so Retief can sneak in, since he's not good at stealthy break-ins like Rioko might be. Perhaps Derwyn could pose as an exotic foreign noble, with Retief's help, so that it doesn't seem suspicious that the pine marten's turned up to a fancy party by himself. Benjy will probably be disguised as a bodyguard, too.
I'm sure a lot of action could go down in such a situation, if one of them is found out by the guards, or if some other dramatic event unfolds.