Series 8’s banger episode Mummy on the Orient Express
is the payoff to a setup most fans probably don’t even remember
happening.

At the end of Series 5 finale The Big Bang over four years
earlier, the Doctor, Amy, and Rory were
about to set off on more adventures when the TARDIS received a mysterious phonecall,
apparently concerning “an Egyptian goddess loose on the Orient Express… in space”

But then… nothing.

While this felt incredibly similar to previous cliffhangers setting up Christmas
specials (minus the WHATs), this phone conversation had
nothing to do with that year’s special, A
Christmas Carol. It wasn’t until
Jamie Mathieson submitted his script for Series 8’s Flatline that Steven Moffat
finally decided to follow-up on The Big Bang’s ending, and commissioned
Mathieson to write an episode called Mummy on the Orient Express.

Smartly, Mathieson even included the surprisingly long wait for this payoff as a plot point, with the Doctor saying that he’s been deliberately
avoiding the phone call – which, from his point of view, happened something like a
thousand years ago. 

So if you ever feel
like you’ve left it too late to text back, just keep this episode
in mind.