Doctor Who deepens the show's central mysteries, and repeats one very high profile old trick

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Three episodes into the new season — four, if you count last year’s Christmas Special as an episode of the new season, which apparently Disney+ does — and it’s clear that Doctor Who is playing multiple different games with the audience at once… and two of them might be the same game, hidden in plain sight.

Spoilers for the Doctor Who episode ‘Boom’ follow. Stop reading now if you don’t want to have the episode spoiled for you. We mean it.

On the face of it, ‘Boom’ is an episode that sees writer Steven Moffat not just return to Doctor Who for the first time since he stepped down as showrunner with 2017’s ‘Twice Upon a Time,’ but return to not one, but two different memorable elements from his time with the show. The central gimmick of the episode — the Doctor steps on a landmine, and the rest of the episode is basically playing out the “how will he get out of that?” question over an extended period — recalls the ‘handmines’ sequences from Moffat’s own ‘The Magician’s Apprentice’ and ‘The Witch’s Familiar’ back in 2015 (nine years ago now!), with both being seemingly inspired by a landmine sequence in the original series’ ‘Genesis of the Daleks’ all the way back in 1975. Oh, and there’s a full-on repeat of the ‘Asylum of the Daleks’ twist, as well… maybe that’s where we should start.

Who’s that girl in Doctor Who 'Boom'?

One of the recurring mysteries of this current season of Doctor Who is just who the old woman who keeps showing up actually is. (Actress Susan Twist has her largest role to date in this episode, playing the AI of the ambulance, not coincidentally.) The idea of a character re-appearing throughout the timeline was central to Clara Oswald’s introduction as the Doctor’s companion, with Jenna Coleman initially appearing, without notice, as a seemingly different character in ‘Asylum of the Daleks.’ That trick is perhaps being repeated in ‘Boom,’ which features Varada Sethu — who has already been announced as a future companion to the Doctor next season — appearing as Mundy Flynn.

Is Mundy Flynn the character who will eventually join the Doctor and Ruby in the Tardis next season? And if so… how? (The answer to that might suggest that we’ll be returning to the conflict of ‘Boom’ before the end of the season, which doesn’t feel entirely unlikely.) Or does she simply share a face with the eventual companion… and if that’s the case, does that mean she’s somehow connected to the mystery of Susan Twist’s character(s)?

(Also, if this is the next companion… Should we be making anything out of the Ruby Sunday/Monday Flynn connection? Even the Doctor points it out…)

What is Ruby Sunday’s story?

This episode is pretty light when it comes to Ruby, but we shouldn’t overlook the fact that the snow keeps reappearing, and entirely outside of her control. (It happened while she was dying and not conscious this episode!) Also worth noting: we’ve now seen both the Doctor and the ambulance scan here, and she seemingly appeared as a regular human to both. So… what is going on with Ruby Sunday? Why is she repeatedly drawn into adventures featuring children (‘The Church at Ruby Road’ with its goblin baby kidnappers, ‘Space Babies,’ which is self-explanatory, and now this?), and how is she making it snow everywhere?

For that matter, is her missing mother either Mrs. Flood from the Christmas Special — someone who seemingly knew more about Tardises than anyone would expect — or Susan Twist’s mysterious recurring character? (Or both?)

Dad to Dad

Not for nothing, but this is the second episode in a row where the Doctor explicitly refers to himself as a parent. He mentioned Susan in ‘The Devil’s Chord’ — his granddaughter, rather than his daughter, admittedly — and then, in ‘Boom,’ he says that he’s talking “Dad to Dad” to John Francis Vater’s AI ghost. That doesn’t feel entirely coincidental, especially given that we’re dealing with stories surrounding children, Ruby’s missing parents, and the Doctor himself talking about being an orphan. We’ve seen the Doctor’s daughter before — in an episode called, of course, ‘The Doctor’s Daughter’ back in 2008 — but we don’t actually know what ever happened to her, just like we don’t know what happened to Susan, either. Could one of them be Mrs. Flood, or the mysterious recurring old woman? Could either be Ruby’s missing mother? Or is all of this one big red herring?

Doctor Who continues next week with ’73 Yards,’ described by Disney+ with the following text: “Landing on the Welsh coast, the Doctor and Ruby embark on the strangest journey of their lives. In a rain-lashed pub, the locals sit in fear of ancient legends coming to life.” The strangest journey of their lives? Considering how old the Doctor is — and how much he’s already seen — it’ll be interesting to see what story can live up to that billing.

If you want to start watching Doctor Who and don't know where to start, check out our handy Doctor Who watch guide. Or maybe you're already finished with the show - We've got the perfect Ten shows to watch when you're done watching Doctor Who guide for you too. If you're already heads over heels for the Fifteenth Doctor and want to learn more about the actor playing him, check out what he's been in before here. Or maybe you just need to figure out how the new series numbering is going to work (Are there really gonna be two series 1s? Yes.) - if so, this is the explainer you want.