Doctor Who: 8 Story Arcs Of The Revived Series Explained

3. He Will Knock Four Times

The End of Time, also known as 'Heartbreak City' (it isn't really known as that, although it should be...), marked the climax of David Tennant's celebrated tenure in the TARDIS and the previous warning that his metaphorical song would end when "he knocked four times" led to the inevitable foray of fevered speculation that the Master would be coming back to kill off the Tenth Doctor once and for all. The Master did return, of course, and he managed to transform the entire human race into replicas of himself in the process, but even that wouldn't prove to be the catalyst of the Tenth Doctor's untimely demise. In fact, the Master (along with an unruly trudge of Time Lords - that really was an eventful episode, wasn't it?) was defeated and banished forevermore into the sealed realms of the Time War and the Tenth Doctor was still alive to tell the tale. Had he defied the odds? Well, no, as it turns out, because David Tennant's contract was still up and so Wilfred Mott went and got himself locked in a glass chamber which, typically, was about to be flooded with lethal radiation. Classic Wilf. He "knocked four times" to get the Doctor's attention - thus fulfilling the aforementioned prophecy - and it was in an act selfless heroism (though he did scream and shout a bit) that the Tenth Doctor came to pass. It was always going to be that way. While "he will knock four times" has been one of the more subtle arcs of the revived series to date, it proved that Doctor Who still possessed the power to shock and break our hearts in equal measure as it kept fans guessing right up until the very end. For one minute there, we really thought it had all been in jest. The Doctor's face said it all.