DISCLAIMER: This recap of Doctor Who Season 1 Episode 3, “Boom,” contains spoilers. Proceed at your peril. 

The prodigal son has returned. Steven Moffat pens an electrifying 48 minutes of television with “Boom.” Seriously, it’s easily Doctor Who‘s best episode since the Twelfth Doctor era. Now, I’m 100 percent biased. I was a Moffat girlie even when it was cool to hate him. That said, the writing is tight, the episode delivers a high-stakes, high-octane narrative and Ncuti Gatwa delivers an incredible performance. It’s award-worthy. I loved seeing a more serious side of the Fifteenth Doctor. I walked away from “Boom” loving him even more. 

This outing brims with Moffat’s signature quirky, clever dialogue. Fifteen sounds a lot like Eleven, but Gatwa makes the dialogue his own. Moffat also deftly balances comedy and drama. I loved the references to Moffat’s era and the little wink to Matt Smith‘s iteration of the Time Lord at the end. 

“Boom” is an absolute banger in my eyes. Side note: Varada Sethu plays Mundy, and we know she’ll be one of Fifteen’s companions next season. Time to theorize, folks… 

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Kastarion 3 

We open on Kastarion 3, with Carson (Majid Mehdizadeh-Valoujerdy) leading John Francis Vater (Joe Anderson) across a smoky battlefield. John went blind due to an injury during this war against the Kastarions. He calls his daughter, Splice Alison Vater (Caoilinn Springall), who’s safely ensconced in a nearby military base. He orders her to “do her teeth” and jokes that he can smell her lack of minty breath via comms.  

John Francis Vater wears soldier's armor, a helmet and bandages over his eyes. He stands beside Carson, who also wears soldier's armor and a helmet. Both are in the middle of a war zone on a distant planet.

DOCTOR WHO Season 1 Episode 3, “Boom.” Photo courtesy of BBC/Disney+.

On the base, Mundy Flynn (Sethu) asks Canto (Bhav Joshi) if he can swap patrol shifts with her. She promises to show him her tattoo — the one she created for someone else. He agrees to switch with her. These two have feelings for each other. We also see that Mundy is a caretaker for Splice while her father is away. 

Carson continues leading John until they spot an Ambulance (Susan Twist). At the same time, Carson falls into a pit, landing on a landmine. Unfortunately, said landmine vaporizes him. Meanwhile, the Ambulance spots John. It sends out grappling hooks, latching onto John. Then, the machine runs medical diagnostics on John and examines him to determine his disease. The machine identifies him and his next of kin before killing him. His cause of death? Blindness.

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Stepping on a Landmine

Then, the Doctor (Gatwa) and Ruby Sunday (Millie Gibson) land in the TARDIS on Kastarion 3. Our titular Time Lord claims he heard someone scream (that was John as the Ambulance killed him). He runs onto the battlefield to track down the source of said scream. Unfortunately, the Doctor, like Carson, steps on a landmine. Uh-oh. 

Ruby leaves the TARDIS to find the Doctor. She overhears him singing “The Skye Boat Song.” Someone’s been binge-watching Outlander between trips across time and space. That’s when Ruby discovers he’s on a landmine. The Doctor urges her to describe what he’s standing on since he knows he can’t look down. The landmine can detect even the slightest movement as it assesses whether the weight on it is a viable target. 

Ruby Sunday and the Doctor stand in the TARDIS, its doors open wide. They have landed on a distant planet with a smoky sky, surrounded by a sandy terrain with stars glowing above them.

DOCTOR WHO Season 1 Episode 3, “Boom.” Photo courtesy of BBC/Disney+.


The Doctor realizes he can’t stand in this position for long. He has one foot on the landmine right now while the other is aloft. Our Gallifreyan needs something with heft to act as a counterbalance so he can put his other foot on the ground. Otherwise, he’ll trigger the landmine and go boom.

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Meanwhile, the Doctor determines the origins of the landmine. It’s from Villengard, the biggest weapons manufacturer in recorded history. If you’re well-versed in Whovian lore, you know Villengard is also a planet at the center of the universe. While it was first mentioned during the Ninth Doctor’s era, we finally glimpsed it in “Twice Upon a Time.” I love that Moffat brings it back here. 

Next, Ruby searches for something heavy for the Doctor to hold. She finds the remains of John Francis Vater stuffed into a canister. Ruby spots drones flying through the air. She sees the Ambulance, too, its blue lights scanning the battlefield for more “patients” to “help.” The Doctor urges Ruby to throw the canister. However, she refuses, deciding instead to approach him. This moment made me stop breathing. Thankfully, Ruby successfully hands the Doctor the canister so he can place his other foot safely on the ground without triggering the landmine to explode. 

The Doctor stands still in the middle of a blazing war zone on a distant planet. He wears a plum-colored velvet waistcoat and tan pants on Doctor Who Season 1 Episode 3, "Boom."

DOCTOR WHO Season 1 Episode 3, “Boom.” Photo courtesy of BBC/Disney+.

John Francis Vater 

Then, the Doctor reads “John Francis Vater” on the canister, bringing about an AI version of the late soldier. The Doctor asks John what happened to him. John states he was “humanely terminated on the discovery of the fatal condition, blindness,” courtesy of the Villengard Automated Ambulance Unit. Suddenly, Splice appears, hearing the sound of her dad’s voice. The Doctor and Ruby avoid telling her that her father died. Splice states that her dad is all she has after her mother was “gathered up” and sent to be with God. 

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Splice barrels into the pit where our fave Time Lord stands on the landmine. She lunges toward the AI image of John. Ruby grabs the young girl, trying to prevent her sudden movement from setting off the landmine. Suddenly, greenish-white light permeates the Doctor’s body. He looks like Carson did before the latter exploded. However, before the Doctor goes boom, Mundy appears. She trains her weapon on the Doctor. 

The Doctor gets her name and jokes that she should marry Ruby, so her name would be “Mundy Sunday.” What a dad joke. Mundy is wary of our Gallifreyan. Canto calls her, revealing he geo-stamped her. He begs her to return to the compound. Oh, and he finally saw the tattoo she gave Posh Graham. She never told him it was on his upper thigh. 

Ruby Sunday wears a red jacket and black jeans. She stands in the middle of a blazing war zone on a distant planet, looking panicked.

DOCTOR WHO Season 1 Episode 3, “Boom.” Photo courtesy of BBC/Disney+.

Not Ordained 

Then, our doc asks Mundy some questions. She reveals she’s an ordained Anglican. Yes, the military and religion go hand in hand on Kastarion 3. Mundy orders the Doctor to drop John Francis Vater’s remains. He’s not ordained, so he can’t hold them. Ruby tells her that the movement could trigger the landmine if he releases the canister. 

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The Doctor questions why Mundy and her squad are fighting in this war. She states that their enemy is the Kastarions, who reside in the mud and the fog. Our Time Lord balks at this, incredulous. Sensing his time on the landmine might end, the Doctor asks Mundy how immolation works. She explains that immolation triggers a quantum-level chain reaction in the victim’s DNA, making them the explosive. 

Next, Mundy fires at his forearm to get him to drop John Francis Vater’s remains. Ruby screams at her to stop. The Doctor vehemently states he’s not a human — he’s a Time Lord, a higher-level being. Since he’s the explosive atop the landmine, not the landmine itself, his death would inevitably destroy the planet. A quantum chain reaction would, in his words, “shatter this silly little battlefield to dust.” 

Combat Detected

Suddenly, the Ambulance approaches, stating “Combat detected” on a loop. The machine launches grappling hooks at the Doctor, latching onto him. Of course, the Ambulance can’t identify him or his Gallifreyan DNA. Ruby grabs Mundy’s weapon, hellbent on getting the Ambulance away from the Doctor. The Ambulance turns on her, detecting combat. Mundy, verifying the Doctor’s statements, offers to help. She urges Ruby to shoot her arm. The setting on her weapon is low, so it won’t hurt her much. 

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Unfortunately, Canto appears at this moment. Thinking Ruby is intentionally harming Mundy, Canto shoots Ruby multiple times with his weapon. She tumbles down into the pit as the Doctor screams. Then, the Ambulance zeroes in on her again, this time grabbing onto her with the grappling hooks to examine her. The machine determines she’s 3,082 years old. The Ambulance attempts to identify Ruby’s next of kin, but, of course, Ruby doesn’t know her biological family. At the same time, snow starts to fall — that pesky snow we’ve seen associated with the mystery of Ruby Sunday. 

Splice Alison Vater wears a yellow jumpsuit. She sits on metal stairs while looking lost in thought on Doctor Who Season 1 Episode 3, "Boom."

DOCTOR WHO Season 1 Episode 3, “Boom.” Photo courtesy of BBC/Disney+.

The Ambulance states Ruby has 432 seconds until she dies. Our Time Lord tries to think of a solution that saves him, Ruby and the planet. Mundy admits he’s right. He’ll blow a hole through everything if they don’t get him off the landmine. Canto attempts to recalibrate the Ambulance so it can revive Ruby, but it’s a long shot. 

Surrender Is an Option 

While Splice remains distracted by the AI of her father (he’s showing her photos from their past adventures), the Doctor orders Mundy to surrender. They should all surrender to the Kastarions. If they’re controlling this technology, stopping the war in its tracks would remove the need for fatal weaponry. 

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The Doctor talks to an unconscious Ruby as she fights for her life. He bounces ideas off her. This is when he realizes that Mundy and her people, the Anglicans, are fighting nothing. There are no Kastarions here. The planet is desolate and empty. War is profitable, and Villengard is making a killing on the monetary front. They implement an acceptable casualty rate algorithm to ensure the right amount of people are dying, making Mundy and the others believe these deaths are from the enemy. 

They fight their own hardware, in the Doctor’s words, and the Ambulances kill just enough folks to make the Anglicans buy more. While most people would notice they’re fighting “smoke and shadows,” the Anglicans have faith. Faith that an enemy lurks in places they cannot see. Oh, Moffat’s here with the religion digs. 

Dad to Dad, Dust to Dust 

Later, the Doctor calls upon the AI John Francis Vater. He asks John to infiltrate the Ambulances and determine if a tangible foe exists on Kastarion 3. John insists this is against his digital protocol. However, the Doctor appeals to his position as a father. Parents will do anything for their children, right? John must do this to ensure Splice has a future. 

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John agrees to this, vanishing to do some detective work. Meanwhile, Mundy chats with Canto as he tries to recalibrate the Ambulance to save Ruby. The pair confess their feelings for each other. Aw. Suddenly, the Ambulance lashes out at Canto, sending him flying across the battlefield. He dies, returning as AI like John. It takes Mundy a moment to realize he’s gone. She sobs. The AI replays Canto’s message to Mundy should he perish. Canto says he loves her. Then, the canister filled with Canto’s remains materializes. Mundy holds it close. 

Here, the Doctor realizes the Villengard algorithm is trying to protect itself. This means that John is infiltrating its systems. AI John reappears; only his time, he seems to be malfunctioning. Villengard has a firewall that’s affecting him. The Doctor urges John to tell Splice to run. Then, the Ambulance appears in the form of an older woman. She insists that any attempts to tamper with the algorithm will receive “severe fines.” 

John Francis Vater wears bandages over his eyes, along with a helmet and soldier's armor. He holds a gun while standing on a battlefield on a distant planet on Doctor Who Season 1 Episode 3, "Boom."

DOCTOR WHO Season 1 Episode 3, “Boom.” Photo courtesy of BBC/Disney+.

Immolation Is Imminent 

The landmine underneath the Doctor’s foot changes color from green to red. Uh-oh. Immolation is imminent. The Doctor orders Mundy and Splice to flee, but the pair refuses, claiming the Doctor’s explosion will destroy the planet regardless. 

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A countdown begins. At this point, multiple Ambulances have surrounded the Doctor, Mundy, Splice, and a still unconscious Ruby. However, now they all say, “Kiss, kiss,” which John said to Splice before he died. John’s infiltration attempt worked. The main Ambulance reverses its death sentence on Ruby. Instead, the machine revives her. She wakes up. At the same time, the landmine is deactivated. The Doctor removes the grappling hooks and steps off it. He embraces Ruby. 

The Doctor thanks John Francis Vater for saving the day — a dad who moved Heaven and Earth to save his daughter. Now, the war is over. Ruby asks the Doctor what transpired while she was out. Our titular Gallifreyan claims he couldn’t explain it with words, but perhaps he could write it in a diary … with drums. Oh, the Eleventh Doctor energy is strong in this one. 

Ruby Sunday and the Doctor look at each other while standing still in the middle of a blazing war zone on a distant planet on Doctor Who Season 1 Episode 3, "Boom."

DOCTOR WHO Season 1 Episode 3, “Boom.” Photo courtesy of BBC/Disney+.

In the End 

Next, the Doctor chats with Splice about her dad. She knows he’s dead, but he’s not gone—not to her. Aw. Later, the Doctor, Ruby, Mundy and Splice gaze upon the ethereal Kastarion 3 horizon. Mundy and Splice hold the remains of their fallen loved ones. Having had enough of that, the Doctor and Ruby depart, bidding farewell to their new friends. Before they go, the Doctor tells Splice he plans to visit Kastarion 3 periodically and that he loves fish fingers and custard—my heart. I miss Eleven so much. 

“We all melt away in the end. But something stays,” the Doctor says. It’s giving, “We’re all stories in the end.” As the TARDIS leaves, a singular snowflake flies toward us. 

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