The Chum Bucket is the name of the fictional location in which Five Nights at the Chum Bucket are set (technically, the two games are in different locations, but they share the same name). The Chum Bucket is Plankton's restaurant.
When the player awakens, they are to find themselves trapped, and located inside the security room in the Chum Bucket. Within the first and second night, the business official who talks to the player discovers that there is another survivor that is trying to save the player. The business official decides to allow the other survivor to come and find the player, in order to kill them both. The player once again has to survive 6 nights against the animatronic onslaught as they wait for their savior, the man behind the door.