'Boom' (Story Code 14.03) by Steven Moffat

“Me. I’m happening. I’m the explosive.” - The Doctor

In 5087, on a war-torn battlefield on the remote planet of Kastarion 3, two soldiers from the Anglican church make their way through the smoke and flames, heading back to their base camp. While Carson frets that the mysterious Kastrions are coming for them, his fellow solder, Vater, ignores his battle-inflicted blindness and calls his daughter, Splice, to promise he will be home soon. Avoiding a nearby Ambulance, a mobile robot controlled by an Algorithm allegedly gone haywire, Carson slips down an incline and steps on a landmine, instantly exploding. Hearing the noise, the Ambulance turns on Vater; deeming his blindness beyond repair, the robot allows him to record a farewell message to his next of kin, and then kills him. Hearing his cry from where the TARDIS has landed nearby, the Doctor rushes to help - only to step on a land-mine too. Joining her friend, Ruby finds the Doctor frozen mid-step, standing on just his right leg for fear of setting off the deadly device. Examining the smart-mine, a product of the weapons manufacturer Villengard Corporation, Ruby sees that its sensors are still green, a few lights still unlit. Hoping he still has time to escape, the Doctor instructs Ruby to find a rock to counterbalance his weight and allow him to put down his other foot. Drones fly overhead and vacuum up the smoke, providing Ruby with sight of her first alien sky. Ruby finds a strange cylindrical object: the compressed remains of Vater; she carefully hands it to the Doctor, enabling him to put his left foot on the ground. The Doctor accidentally activates the AI connected to the cylinder, which plays a hologram of Vater’s final words. Vater’s daughter appears from over a ridge, having heard her daddy while out searching for him. Seeing her father’s image, Splice gets dangerously close to the Doctor; Ruby manages to stop Splice in time, but the stress on the Doctor causes more lights to activate on the mine. The Time Lord starts to glow - the mine is altering his DNA to make him the explosive. The group are joined by Splice’s friend, an Anglican marine named Mundy Flynn. Having never seen a Kastarion, the soldier levels her gun at the Doctor and orders him to drop the cylinder; when the Doctor refuses to comply, Mundy shoots his arm. The Doctor desperately tries to remain still and calm, warning that if the smart-mine causes a quantum-level chain-reaction in his alien DNA, the resulting explosion would destroy half the planet. An Ambulance arrives on the scene and connects itself to the Doctor to begin its triage. To draw the Ambulance away, Ruby grabs Mundy’s gun and starts firing; Mundy tells Ruby to shoot her a bit, hoping the injury will distract the Ambulance – but then Mundy’s comrade, Canto, arrives on the scene and shoots Ruby point-blank. While the distraught Doctor struggles to remain calm, the Ambulance analyses Ruby, determining her to be 3,082 years old with no next of kin, and therefore beyond financial benefit. Snow starts falling, then freezes in mid-air as Ruby’s life starts to fade. As the shock hits the Doctor, more lights activate on the mine, and a five-minute countdown begins. The Doctor tells Munday to make the Anglicans surrender: with no war, their landmine will deactivate. The Doctor has worked out what caused the war: when the Anglicans arrived on Kastarion 3 six months ago, they announced their presence with gunfire - but the planet was unpopulated; with no enemy, the Algorithm kept the soldiers fighting a non-existent foe, just so that Villengard could turn a profit from the weapon sales. The Doctor proves his theory to Mundy by instructing Vater’s AI to download itself into the Ambulance via its connection to him and check its Algorithm. While Canto tries to reconfigure the Ambulance into saving Ruby, he and Mundy confess their like for each other; but their love is doomed, as the Ambulance electrocutes Canto, compressing him to a cylinder, and playing his last words via an AI hologram. More Ambulances arrive and close in on the group. Detecting Vater’s presences in its system, the main Ambulance deems him a hostile virus and tries to delete him. The landmine finally activates, its lights turning red and the final seconds counting down... But instead of exploding, the mine deactivates - Vater’s AI has overridden it, along with all the Ambulances! To the Doctor’s delight, Vater uses the Ambulance to revive Ruby, before ordering the end of the war… Later, the Doctor, Ruby, Splice and Mundy watch a peaceful new day dawn Kastarion 3. Proud of her father’s actions, and with his memory preserved in an AI hologram, Splice stays with Mundy. Promising to return to check up on them, the Doctor and Ruby depart in the TARDIS.


Ncuti Gatwa (The Doctor), Millie Gibson (Ruby Sunday), Joe Anderson (John Francis Vater), Majid Mehdizadeh-Valoujerdy (Carson), Caoilinn Springall (Splice Alison Vater), Varada Sethu (Mundy Flynn), Bhav Joshi (Canterbury ‘Canto’ James Olliphant), Susan Twist (Ambulance)

Directed by Julie Anne Robinson

Produced by Vicky Delow
Executive Producers Russell T Davies, Julie Gardner, Jane Tranter, Joel Collins, Phil Collinson, Julie Anne Robinson and Steven Moffat
A Bad Wolf / BBC Wales production

TX (BBC 1 & BBC 1 HD):
18th May 2024 @ 6.50 pm


Notes:
*Featuring the Fifteenth Doctor and Ruby

*This episode is forty-four minutes long

*Varada Sethu was not credited in TV listings, to preserve the surprise of her appearance ahead of her expected introduction as a new companion later in the series

*There’s Always a Twist at the End: Actress Susan Twist appears again, this time as the Ambulance AI

*The episode premiered in the UK on the BBC's iPlayer in Ultra-High Definition (UHD) at midnight on 18th May 2024, and simultaneously streamed on Disney+ outside the UK and Ireland