M046 - Flip Flop

Finally a story that addresses the time loop issue. Pity it reveals just why time travel writing usually avoids it: annoying repetition. Like the film Vantage Point, which continually rewound itself to show different characters' points of view, Flip Flop suffers from repeating sequences when the time travellers return to places they have been before.

The story starts in the middle of things and the Doctor and Mel are stepping out of the TARDIS to hear their names being called out in an Orwellian police announcement. Joining up with a pair of terrorist/assassin/time travellers, the Doctor and Mel are forced to take them back in time 30 years to assassinate the President before she makes a decision that leaves the planet in the hands of unpleasant slug overlords.

The ripple effects of their actions are revealed when they all return to the present and find it drastically altered, but for the worse. And here the time loop problem reveals itself. When you change something in the past and return to the present, a new you exists. Now the terrorists are disaffected lieutenants in the military and the Doctor and Mel have to leave before the other them arrive in their place...

Which they do, in the middle of a police alert looking for them. And then they meet up with a pair of disaffected lieutenants who want to go back in time and stop the assassination of the president to undo what has gone so wrong the past 30 years, oblivious to the fact they are to blame.

It's nice to know that the writers considered this problem, and it is a clever idea to have an infinite loop of the Doctor and Mel arriving and switching the planet's history and leaving again before a past version of themselves arrives and does the opposite, but since the whole thing essentially repeats itself (with the same sort of questions being asked and the same sort of conclusions being reached by the Doctor), it all feels a bit redundant.