Malisker approaches us with a mission - it turns out there's an object in
his possession that he's trying to get out of the keep.  With the ambush
gone, he's hoping he can make the trip safely if he leaves immediately,
but he's worried that there are spies in the keep who'll report his
departure and this will lead to other arrangements being made.  So,
he wants us to keep watch to see who, if anyone, follows him out of
the keep.

First watch, Rimardo watches the front gate.  The first person to try
and get out is the weedy guy we'd run across in the tavern.  He clumsily
manages to bribe his way out (as no one's allowed to leave or enter
the keep at night).  A bit later, Malisker and his six men leave, and
Rimardo passes a note to him mentioning the earlier departure.  However,
despite the watch they keep, none of the group notice anyone else leave
the keep that night.

The next day, Lam talks to Kendrion Felder, the person who bribed his
way out the night before.  Turns out, he has a thing for spiders.

The actual spy is Inglor, a dwarf.  We end up fighting him, a hag, and a
deep one.  Inglor turns sides when he finds out who he'd actually been
working for and, after we win the fight (1100 xp, maul of swimming)
tells us about the group he thought he'd been spying for, upstream
bandits posing as mercenaries (the hag had been his contact).

Malisker gives us a 100 gp reward for dealing with the hag.

The haunted keep the map we'd found earlier turns out to be Riverguard,
old and supposedly abandoned, but often home to river bandits, as it
seems it is once again.  Their leader is Jolivar Grimjar.

(There's a statue of a deep one that came from a sinkhole along with
the hag.  Exposure to it had turned someone into the deep one we fought.)

(Reference to Feathergale Spire, ~10m east of Red Larch.)

Dealing with river bandits (on the river, even!) yield 500 xp.