The Sea Devil's Stout

From the introduction:

The signs says, "The Sea Devil's Stout". A series of rope bridges lead out to what appears to be an inn atop a spit of rock. A woman begins to scream. The screams come from the inn.

Ingrid, the distraught innkeeper, claims giant rats dragged Ziggy, her small child, down into the basement.

She says she has only recently become the innkeeper and is unaware of what is beyond the second storeroom. She pleads for help in recovering her child. She can offer some gold as a reward, but not much.