Doctor Who: Every Series 3 Episode Ranked From Worst To Best

This two-parter, rather brilliantly, opens rather cold. There's no immediate explanation for why the Doctor appears to be a teacher in 1910s England having dreams about a life he clearly doesn't believe he lives. As it turns out, the whole situation is the Doctor forcibly lying to himself, hiding his identity inside of a Time Lord fob watch to hide from the vicious Family of Blood.

The story plays out with perfect pace as Martha does her best with the responsibility she has to keep the Doctor and the people around her safe, even as the Family drawer nearer. The episode touches on British pre-war sensibilities and love, as the Doctor's persona as John Smith falls for Joan, the school nurse.

David Tennant is simply stunning in this episode, playing a totally different character and imbuing them with a different energy than we're used to seeing. John Smith is awkward, a romantic, and - at least by comparison to the Doctor - a bit of a coward in the face of his mortality. Human Nature / Family of Blood centre on making the right decision, what it means to be alive, and the internal struggle of one man who may not even be real.

Jessica Hynes and Harry Lloyd's brilliantly realised characters just add more believability to a story that is frightening on the surface and shockingly deep beneath.