Costume Quest 2 takes place after the cliffhanger ending of the Grubbins on Ice DLC for the original Costume Quest. The kids go through one of the portals, only to find themselves in the past, on the Halloween of their first adventure. They see a dentist use a portal to travel through time, causing Halloween to be outlawed, and also causing the Grubbins to live among the humans. The twins, Wren and Reynold, are visited by the future adult versions of their friends, who send them through a portal to try to stop the dentist from going through with his plans. Wren and Reynold must go through three time periods, meeting a new friend in each time who temporarily joins their party. They battle monsters, in turn-based battles with quick time events to increase power and defense, in order to save Halloween.