In separate interviews, Steven Mofatt, who penned the Doctor Who 2024 series episode Boom, and Doctor Who showrunner Russell T Davies offered some information on what to expect from the third of the eight-episode series.

In Boom, the Doctor and Ruby are caught in the middle of a devastating war on Kastarion 3, a world on the farthest edges of the galaxy. The Kastarions themselves can’t be seen, hiding in the fog. The planetary battlefield is all traps, smoke, mud, danger an ruins and the Doctor is trapped when he steps on a landmine set to explode when he removes his foot. The Doctor (Ncuti Gatwa) must hold his nerve to save himself and Ruby (Millie Gibson), plus the entire planet… without moving. In the midst of this, the Doctor and Ruby meet someone who might, one day, change their lives forever.

In a BBC interview Steven Moffat had this to say about his episode and Ncuti Gatwa’s Fifteenth Doctor.

“Tension, emotion and the Doctor afraid. Putting the Doctor in absolute jeopardy and making him afraid, you get to see that side of him. The Doctor is not in control of the situation and he cannot do anything – he can’t help people, he can’t shove his way to the front and flourish his screwdriver and make something go away. He can do nothing as he can’t move.”

“…once the crisis hits, the Doctor is the Doctor, the ancient general rises to the surface and he’s commanding, terrifying and compassionate in the long term, but not always in the short term.”

Russell T Davies gave a primer and a warning about the name of a character in Boom for on the official Doctor Who podcast.

“We’re on a war-torn planet, Kastarion 3. It is bleak, it’s scary, it’s muddy, it’s foggy, it’s dangerous and that throws [the] Doctor into the most extraordinary situation in which both he a Ruby have to act at the height of their powers and use all their wits to escape from this. It’s a great supporting cast and there’s a great supporting character called Splice and one thing I would say in this story is be very careful about saying Splice’s father’s name out loud.”

According to the cast list for Boom, Splice Alison Vater’s (Caoilinn Springall) father’s name is John Francis Vater (Joe Anderson). In a clip from Boom on the official Doctor Who podcast, he is seen in a battle zone admonishing Splice to brush her teeth via an implanted audio comm system. The soldiers all wear clerical collars.

At another point in the episode, Vater is seen receiving a painful medical procedure from a battlefield robot ambulance with a human face (Susan Twist) on its screen interface – as seen from a clip on Doctor Who: Unleashed.

On the surface, there doesn’t appear to be anything unusual about the name John Francis Vater. Fans will need to watch Boom to discover why speaking his name out loud is dangerous.

Boom, written by Steven Moffat and directed by Julie Anne Robinson, will stream on 18 May 2024 midnight, 00:00 BST (17 May 7:00pm ET) on BBC iPlayer in the UK and Ireland and Disney+ everywhere else, where available. Boom will also broadcast on BBC One in the UK on 18 May at 6:50pm. On subsequent Saturdays, the remaining episodes in the series will stream on iPlayer and Disney+ at 00:00 BST and will broadcast in the evening on BBC One.