The phrase "dark cellar" refers to a storage space underground that is poorly lit or without any light. It often conveys a sense of gloominess, mystery, or hiding something. Full definition
This I could understand more if he'd been trying to play some strange system concocted with Franco Baldini in the deepest darkest cellars of the FA. (caughtoffside.com)
Why am I locked in a dark cellar surrounded by things that degrade and dehumanize me? (nakedpastor.com)
«Theology is never any help; it is searching in a dark cellar at midnight for a black cat that isn't there. (religion.blogs.cnn.com)