Doctor Who: 10 Revived Series Episodes You'll Only Watch Once

6. The Unicorn And The Wasp

There's nothing wrong with this episode as a whole but, like all good murder mysteries, it's just not the same when you actually know whodunnit. Part of the fun is watching it for the first time and trying to piece together all of the clues as they unravel (spoilers: you'll probably work it out way before the rest of them do) so as soon as the culprit has been revealed, there's really no need to sit through it all again. If you were to revisit The Unicorn and the Wasp, though (and coincidentally it was recently picked as one of our most underrated NuWho episodes), it would be for David Tennant and Catherine Tate's reactions to the ensuing drama. They're both on top form throughout the episode, particularly Catherine whose response to the Vespiform ("It's flipping enormous!") is fondly remembered as one of Donna Noble's most memorable moments. And then there's Agatha Christie, of course, played by Fenella Woolgar. The episode adds its own sci-fi spin to the author's mysterious disappearance in 1926 but if you're not really interested in the life and times of the crime novelist, most of that sub-plot will probably go straight over your head. Don't expect the rest of the plot to be as interesting as it was the first time on repeat viewings, either. As Agatha herself rightly points out, "The thrill is in the chase, never in the capture", and unfortunately it's one of those episodes that you can only chase once. The capture, while a satisfying pay off, does lose its 'sting' rather quickly after that. Ba dum tss!