There’s something comforting about a good detective story. As an aspiring Baker Street Irregular, there is no greater joy than the existence of something known as the ‘Holmes Moriarty Game’. There’s a lot to be learnt from Arthur Conan Doyle’s Sherlock Holmes, most prominently the ‘science of deduction’. But breaking down Holme’s approach to deducing the background and narratives of his clients and of crime scenes, brings us to a basic tenet of Probability Theory. “When you have eliminated the impossible, whatever remains, however improbable, must be the truth.”