Batman works best when he has a mystery to solve. That should be a given, really, seeing as how the World's Greatest Detective originated in the pages of Detective Comics some eighty years ago, but not every Batman comic has managed to weave a particular mystery. When one does, it becomes a proper event.
The Dark Knight is a superhero first and foremost, but nothing beats a good mystery - especially when he's in the driving seat. Across multiple comics and eras, the Caped Crusader has unmasked more villains than Mystery Inc. and blown the lid on conspiracies aplenty. He's an expert at multiple investigation techniques, and never gives up, no matter how insurmountable the odds may seem.
Whether he's going undercover as Matches Malone or interrogating criminals one by one, it's inevitable that Batman'll get to the bottom of any mystery, even if he himself happens to be implicated as a victim.
But it takes a particular kind of case to test the Dark Knight. Naturally, that tends to mean that the mysteries he's featured in can often border on the insane, with many able to keep readers guessing until the very last page. Here are the stories that achieved that feat, and managed to blow all our minds in the process...