It's not unusual for a new Doctor Who episode to have fans picking over a particular plot point from the show's long history, but viewers of the most recent outing Praxeus have a very specific quibble related to a classic story.
In short... why didn't the Doctor save Adric?
Let us explain: in series 12's latest, troubled policeman Jake (Warren Brown) attempted to pilot a damaged spaceship, in order to help spread an antivirus across Earth that would combat the deadly Praxeus pathogen.
Jake succeeded, but appeared to be doomed when the ship around him started to break up. Luckily, the Doctor was able to materialize the TARDIS around Jake, rescuing him milliseconds before detonation. Hooray!
Fans, though, were quick to point out the similarities (and one key difference) between Jake's fate and that of Adric (Matthew Waterhouse), a companion who travelled with the fifth Doctor (Peter Davison) in the 1980s.
The 1982 story Earthshock saw Adric trapped on a freighter which collided with Earth, with the Doctor apparently unable to save him. Adric perished, one of the few Doctor Who companions to be definitively killed off.
So what gives? Why did Jake get saved, but Adric didn't?
Well, there is actually a very reasonable explanation...
In the moments prior to Adric's demise on the freighter in Earthshock, a squad of Cybermen invade the TARDIS and, in the resulting scuffle, the ship's controls are damaged.
This oft-forgotten detail is why the fifth Doctor couldn't save his friend. If the TARDIS had been in full working order, then he might indeed have been able to pull off a trick similar to the one that saved Jake...
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So blame those heartless Cybermen for this one – they'll be returning to Doctor Who later this series and will reportedly be more "ferocious" than ever.
Doctor Who continues on Sundays at 7:10pm on BBC One