Doctor Who: Every Series Plot Thread Ranked Worst To Best

Back in the day when long-running threads in Doctor Who were still pretty green, there was a one-word mystery which eventually took on a life of its own. Turns out that Torchwood, (anagram for "Doctor Who", in case you didn't already know) pertained to a government facility that specialised in anti-alien military defence. This in turn led to a swift invasion from both Cybermen and Daleks, in what is still one of the best two-part Doctor Who finales of all time.

After that, Torchwood was seldom referenced... in Doctor Who at least. It did however land its own show which ran for two seasons and a two subsequent high-budget mini series'.

It saw Captain Jack, one of Doctor Who's most loved characters, take centre stage and embark on some exploits way too adult to be covered on prime time. Conceptually, it moved far pretty far away from its original source, but in doing so, cemented a respected legacy in its own right.

Not a bad run, seeing as it was first referenced on a deep-space version of The Weakest Link.