Detective Comics #175 (1951)

Detective Comics #175 from 1951 tells the thrilling story of "The Underworld Bank," starring the Dark Knight himself, Batman. A curious trend has arisen lately - convicted criminals keep insisting that they can't remember where they stashed the loot from their crimes, but they are all found with suspicious-looking keys on them. Batman does some digging and discovers that these keys are all actually safety deposit box keys - but not to any known bank. Intrigued, Batman sets out to investigate, leading him to companies that manufacture bank vaults and ultimately, to a shocking discovery: the keys match those to a bank that was supposedly sold for export but in actuality was installed under a warehouse belonging to the criminal underworld. This is a must-read for any true comic book fan!