For some folks, mysteries are two-sided stories. There’s always the central puzzle to solve: usually who left a corpse (or corpses) laying around. Then there’s the motive behind the misdeed. But what keeps a lot of mystery readers glued to the page is the thrill of the chase. They stay awake for hours, mentally following a Sam Spade or Cormoran Strike from one risky scenario to the next, taking on all comers in a fight to the finish. It’s grand entertainment when it’s done right. But they’re not on the menu today. This is a salute to the mega-brains of detective fiction, those sleuths who never break a sweat. Literature refers to them as “arm-chair detectives.” They’re Sedentarians, to me. I know a bit about Sedentarians from my father’s side of the family. I saw them in action, so to speak, as a kid. Yes, my dad’s folks were farmers originally, but whenever we went for a visit, the family got together and sat. And sat. For hours on end. Until, if sitting was an Olympic Sport, my family would all have been medalists. But, however stationary my relatives could be, none of them were a patch on Mycroft Holmes. If you…