While investigating a slaver ring, the heroes are lured into the clutches of the rat king and tossed into his dungeon bereft of equipment. Do they have the mettle and wits to escape? Revenge of the Rat King is a 5E adventure designed for four to six 5th-level characters, who will advance to level 6 before the adventure's conclusion. While any combination of character classes can undertake this challenge, rogues and sorcerers will prove extremely useful, and a party with a wide range of skills will have the best chance of survival. Above all, teamwork will be essential to the heroes' success.