Bloody Human

This was a mid-season two-parter, with Part I being titled "Human Nature" and Part II titled "Family of Blood." The premise is that the Doctor and Martha are being chased by some aliens known as "The Family" who have a fairly limited lifespan, that is unless they can feed off the Doctor's Timelord energy. Despite their "mayfly-like" lifespans, they can apparently track the Doctor anywhere in time and space - so he and Martha need to hide somewhere and wait out the aliens' lifespans (which is only a couple months or so). However, the Doctor's biology is too unique and would allow them to easily find him no matter where he goes - so the Doctor uses a contraption he "never thought he'd have to use" to re-write his own biology to that of a normal human being. He stores his Timelord consciousness in a device that looks like a normal pocket watch. Then he and Martha hide out in 1914 Great Britain - with the Doctor playing school teacher, and Martha as a maid (having to endure the racism of the era as well). Problems arise because the Doctor doesn't remember who he is, falls in love with the school nurse, and Martha fears she's losing him. She's also pissed off that he's fallen in love with someone other than her. The Family does track them down, however, because the watch with the Doctor's conscience is stolen by a school boy who opens it. He's kinda psychic anyway, apparently, and can "hear" the Doctor speaking to him from the watch. The Family each steal the bodies of some locals, animate an army of scarecrows, and go about killing people until the Doctor accepts that he is not human, downloads his true self from the watch, and tricks The Family consequently blowing up their cloaked space ship. But not before the Doctor gets a glimpse of the life he might have had as a human - with a wife, kids, grandchildren, and a death in old age. YAWN! The Doctor deserves better than an average, boring, early 20th Century life! Thankfully he's never relegated to that mundane existence. The Family, however, realize that when the Doctor ran from them he wasn't doing so because he feared them. "He was being compassionate." Because the Doctor gives the members of the Family what they wanted - IMMORTALITY - just not how they wanted it: trapped in mirrors, eternally falling into the event horizon of a black hole, perpetual (but apparently conscious) stasis as a scarecrow - you know, that sort of thing. All in all not a terrible story, and it did revisit the Doctor's claim that he has little mercy left for such evil-doers.