This is a good adventure for someone who is newly arrived in Dereth.
An old timer recently came through town and told me what he remembered about the Guerin family's plans to move down here from Rithwic. They dug the basement for a modest house, but then Old Guerin lost all his money in an ill-fated dice game.
They abandoned their plans and, well, lots of red rats have made their lair in that old basement of theirs now ... If you want to take a look, the entrance is at 21.1S 2.2W.