Doctor Who Season 14 Episode 3: ‘Boom’ ending explained

The third episode of Doctor Who Season 14 is a simpler affair, with the Doctor rooted in place by a trigger-happy landmine. Here’s everything that goes down in the climactic ‘Boom’ ending.

When the Doctor and Ruby Sunday first arrive on Kastarion 3, the Doctor is quickly incapacitated by stepping on a landmine. Unable to move, he and Ruby find themselves trying to save him and solve the mystery of the ongoing war between the human Anglican soldiers and the unseen Kastarions.

The ‘Boom’ ending sees the Doctor unraveling the tragic truth about the war, all while grappling with the stress of his entrapment and his guilt surrounding Ruby, who was mistakenly shot by a soldier.

The clock is constantly ticking in this hair-raising Doctor Who episode, and we’ve got everything you need to know about what happens in the ‘Boom’ ending. (Warning: major spoilers ahead!)

How does Doctor Who Season 14 Episode 3 end?

Episode 3 ends with John Francis Vater’s hologram infiltrating the Villengard algorithm and shutting it down from the inside, effectively ending the war on Kastarion 3 and allowing the Doctor to step off the landmine safely.

Let’s walk it back for context; by the time the episode starts to wrap up, things are looking dire for everyone involved. Ruby is on death’s door, having been shot by Canterbury (an Anglican soldier), and the Doctor is within an inch of being detonated — which would destroy half the planet, given his biological impact.

The Doctor has already worked it all out. As he explains it to soldier Mundy Flynn (played by Varada Sethu — yes, that’s right! Future companion alert?), there is no war against the fabled Kastarions — in fact, there are none. The Anglicans have effectively been fighting against themselves for decades, having been tricked into declaring war on an empty planet.

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The Villengard algorithm did this in order to keep making a profit on weapons manufacturing. As the Doctor tells Mundy: “You’ve been fighting smoke and shadows.”

But Mundy tells him that only the Bishop can declare a surrender, and they’ll need evidence to prove it, so the Doctor convinces the hologram of the long-dead John Francis Vater to download himself into the Villengard algorithm and find the proof they need.

A fallen soldier

While Mundy and Canterbury (nicknamed “Canto”) are attempting to reconfigure the Villengard ambulance unit in order to help Ruby, Canto reveals that he likes Mundy. However, the ambulance’s defense system is activated, blasting them both and killing Canto.

His hologram appears, delivering a message to Mundy, his “designated favorite person.” He tells her he loves her and gets turned into a casket, which is the ambulance’s way of disposing of bodies.

The algorithm can sense what John Francis Vater is trying to do, and is beginning to defend itself. Soon, the Doctor, Mundy, and John’s daughter, Splice, are surrounded by multiple ambulances, all ready to strike. The system attempts to delete John Francis Vater, all the while the Doctor’s landmine is fast approaching the fail-safe, which will result in detonation even if it can’t detect him.

John Francis Vater saves the day

He tells Mundy and Splice to run, but they refuse — they’d never get far enough in time. Feeling the failure, the Doctor apologizes and prepares to be detonated.

But when the countdown reaches the end, John Francis Vater’s signature message to his daughter — “Kiss, kiss” — can be heard. The ambulances soon join in, and it’s clear that he’s successfully taking over.

With the system finally on their side, the ambulance revives Ruby. What’s more, the landmine is deactivated, allowing the Doctor to finally step off. Overcome by joy, the Doctor is thrilled by the realization that the powerful war algorithm was simply overthrown by a father looking to protect his child.

War is over

John Francis Vater’s takeover essentially means that the war is shut down. Peace finally comes over Kastarion 3, and the Doctor, Ruby, Mundy, and Splice stand and look at the sky, which is now clear from the fog. Mundy will look after Splice from now on, and although Splice is aware that her father is dead, she maintains that he isn’t gone.

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The Doctor and Ruby head back to the TARDIS. Ruby is unconvinced by Splice’s outlook on Death, as John Francis Vater is definitively dead. In turn, the Doctor tells her that “we’re all dead eventually,” and quotes poet Philip Larkin (who he met, apparently) by saying: “what survives of us is love.”

After the two wave goodbye to John Francis Vater’s hologram, they step into the TARDIS and it disappears, but not before a snowflake falls right into the camera, indicating that, with every episode that passes, the mystery surrounding Ruby’s past deepens.

That’s the ‘Boom’ ending! For more of the latest season of Who, take a look at our ‘Space Babies’ ending explained and ‘The Devil’s Chord’ ending explained. You can also get a full breakdown of Susan Twist, who plays the ambulance in this episode.

Don’t miss when the new Doctor Who episode is coming out, too!