"The Old Castle's Secret" is a 32-page funny animal comic book adventure/mystery/horror story written, drawn, and lettered by Carl Barks. It was first published by Dell Publishing in Four Color #189 (June 1948). Characters include Uncle Scrooge, Donald Duck, and Huey, Dewey, and Louie. The story is about a treasure hunt led by Uncle Scrooge through an old castle in Scotland. It is the first of Uncle Scrooge's comic book treasure hunts. The story was published with three one-page gag stories by Barks. The cover is the first comic book cover ever drawn by Barks. The story has been reprinted many times.