Als ein seltsamer Dämon namens Krampus auftaucht und die Kinder der Stadt in Angst und Schrecken versetzt, wollen Fred und die anderen die Sache einmal genauer unter die Lupe nehmen. Was könnten die Motive des Ungeheuers sein und wer steckt wirklich dahinter? Doch wie so oft ist nicht alles so, wie es auf den ersten Blick scheint, denn Fred und seine Freunde sind ganz schön ausgefuchst.
A teenager vandalising a neighborhood is attacked by a creature calling itself "Krampus," leaving his hair snow-white with fear. Three more kids are attacked as the gang meets Mayor Nettles and Sheriff Stone at the roller rink and arcade. Realizing that Krampus attacks "bad kids" such as the aforementioned teenager, the gang turn to the imprisoned Mary-Ann Gleardon for help only to have Krampus attack and kidnap her from prison. In the end, it's revealed that the gang had enrolled the forces of Hot Dog Water, Jason Wyatt, Mary-Ann Gleardon, Ex-Mayor Fred Jones Sr., and Charlie the Robot (from the Haunted Museum exhibition) in an elaborate scheme to steal the original Mystery Incorporated's pieces of the Planispheric Disk. After the gang reassembles the disk, the eyes of the Crystal Coffin glow and it mutters "Nibiru."
יצור בשם קרמפוס תוקף תושבים בעיר כדי להעניש אותם על התנהגות לא טובה. תאגיד המיסתורין יוצא לחפש אותו ולפתור את התעלומה.
I ragazzi riescono a truffare la vecchia gang, distraendola mentre i suoi membri ne recuperano i pezzi del disco per comporlo una volta per tutte.
Quando um demónio maléfico chamado Krampus começa a atacar os jovens mal comportados da Enseada do Cristal, o grupo da Mistério S.A. investiga.
Quando um demônio malvado chamado Krampus começa a aterrorizar as crianças travessas da Baía Cristal, a turma se prepara para desvendar mais um mistério.
