10 Best "Everything You Know Is A Lie" Moments In Doctor Who

Don't deny it - at some point in our lives, we've all suspected that we might be part of a Matrix or Truman Show scenario, where our existence isn't what it seems.

Bill and Nardole find themselves in the middle of that situation in Series 10's Extremis, where they stumble across a group of suicidal scientists, who are about to blow themselves sky high because they believe their world isn't real.

To demonstrate why they believe this, one of the scientists gets Bill and Nardole to take "The Shadow Test". They both pick a random number and say it at the same time, and - bizarrely - they both say the exact same number every single time. A bit like the Midnight entity repeating everything.

Suitably spooked by this turn of events, Bill and Nardole retreat to a reused set from The Girl Who Waited (we kid, but wait, is it?), where Nardole deduces that they're basically in a video game. Confirming this suspicion, he's melted into pixels when he tries to escape the confines of this very much virtual reality.

Those scenes of mass suicide are incredibly dark for Doctor Who, and the reveal that our characters are essentially onboard the Holodeck is a strong moment in one of the best episodes of Series 10.