“Hello. We are looking for highly intelligent individuals. To find them, we have devised a test.” These words, found in a message posted on 4Chan in January 2012, started a global ‘treasure hunt’ – with thousands of puzzle-loving and curious individuals desperately competing with one another to be the first to crack the devilish puzzles created by the mysterious Cicada 3301. Who is Cicada, and what are their goals?