Mycroft Holmes is a very old man who calls himself Professor Lazarus - nice subtlety there, BRAVO RTD GATISS Greenhorn, actually! He invents a big spinny-thing to make himself middle-aged again (why not 20?), but it changes him into a poorly-rendered video-game scorpion monster. He dies, then kills some ambulance dudes then dies again and is naked in a very cold church at like 3 AM. There’s also some stuff going on with Martha’s family but it’s not terribly interesting and if you’re watching this out of order from the rest of the season, you’ll give zero fucks.