The Sewer Fiend d20 system adventure is Series III, Number 2 of the Legends & Lairs Instant Adventure product line, and is designed for 4–6 characters of levels 5–7. A very linear scenario with an impossible-to-catch cat that leads the PCs through a small dungeon where they stumble into the laboratory and fledgling army of an evil spellcaster. Has a new monster (the "ratling"), and a new spell.

From the back cover:

Noribudn. Commandant-Burgher of Vallidyl, paced nervously around the empty council chambers in the city garrison. "I'm surprised you're not worried," he told his daughter, who draped herself over one of the tall-backed chairs reserved for other burghers. "I haven't seen Jasper for days."

"Dad, it's just a stupid cat. I'm a grown-up girl now. I'm done playing with dolls and silly pets. I wish I had more responsibility, like you."

"Running this city and defending it from outside threats is no work for a young lady like you, Carnelia."

"Just forget about it." Carnelia heaved herself out of the chair and stomped out of the council chambers.

Noribund stroked his beard, mumbling to himself. He suddenly stopped pacing and called out for his clerk. "Benthric! Visit the taverns and hire some compentent mercenaries."

"But sir, the guard has reached full capacity, the barracks are crowded, and we have no more equipment for new recruits."

"I want them to find out cat. Jasper's just as much a part of my family as Carnelia. We would all be crushed if something terrible happened to him," Noribund said, wringing his hands. "Offer these people 200 gold up front and another 800 gold when they return Jasper alive. He's a brownish tabby with a bit of a paunch. A silver tinkling bell hangs form a silk collar around his neck."

"That should be sufficient, sir." Benthric began sneaking off. "I'll make the necessary arrangements, and see that your adventurers begin their search for poor Jasper as soon as possible."