The TARDIS materialises in Miami in 1952 and, after donning appropriate outfits, they venture outside where the Doctor sets up a Vortex Indicator, or "Vindicator". Positioned at various locations in time and space, these should work together to guide the ship to London in May 2025.
It is 4am and they have arrived outside a boarded-up cinema - the Palazzo - which intrigues the Doctor, after reading a note left with some flowers. The last movie to play here was a Rock Hudson feature called The Harvest Bringer. Some of the marquee display letters have fallen away.
They go to a nearby late-night diner, which should enforce segregation, but the young man serving - Logan - is happy for them both to come in. He tells them of how fifteen patrons vanished from the cinema one morning some 3 months ago. There is only one other customer, a woman named Renée Lowenstein. She comes here every night as her son, Tommy Lee, was one of those who disappeared. Seeing the Police Box, she thinks that someone has finally taken note and come to help, and the Doctor assures her he will find her son.
The Doctor learns that the cinema is not empty. The projectionist Reg Pye, is always there.
They break in and meet Reg, who tries to warn them to leave. He starts talking to some unseen person - asking them not to hurt the newcomers. They hear tap-dancing coming from somewhere, and then see a spotlight hit the cinema curtain. A cartoon starts up, featuring a character named Mr Ring-a Ding who sings and dances.
They are shocked when the figure then begins to address them directly. The Doctor ascertains that this is not a hologram, and asks if it knows what happened to the missing audience members.
Mr Ring-a-Ding answers only in riddles and corny jokes. Outside, on the cinema marquee, further letters fall away to leave HAR - B - INGER. The Doctor tells Belinda that the Gods of Chaos employ Harbingers to pave the way for their appearance. The cartoon figure announces that he is Lux, Imperator - the God of Light. Having spotted that he has to complete his song whenever he launches into it, the Doctor realises that this delay will give them time to escape.
They go to the projection booth and speak to Reg, curious to know why he wasn't taken like the others. He reveals that Mr Ring-a-Ding needs him to play movies in order to feed him the light he craves. He tells them the story of how he lost his sweetheart many years ago, but Mr Ring-a-Ding has brought her back to him - captured forever on film. He reveals that this was the fate of the missing people. They have also been trapped on celluloid.
Mr Ring-a-Ding is able to leave the screen and walk up to the booth, threatening to burn all the celluloid in the room if Reg helps the Doctor and Belinda any further. He tells them that he was created by chance, when moonlight bounced off a spoon and passed through the projector as a Mr Ring-a-Ding cartoon played.
He then turns the two projectors on them - turning the Doctor and Belinda into animated figures on the big screen. They find themselves trapped in 2-D bodies. The Doctor realises that they are contained within frames of film, and if they can break these then they may be able to escape.
They are able to drag the film frame edges down and tear them apart, and find themselves back in the cinema. They are then confronted by an armed policeman who is accompanied by Mrs Lowenstein. She accuses them of being troublemakers who claim to know what happened to her son, so must be involved in the disappearances. The Doctor spots a discrepancy straight away. The officer is wearing a New York Police Department uniform, yet they are in Miami-Dade county. They are still within a film. This time they decide to push their way out of it. Climbing through an aperture they find themselves in a 21st Century living room - having just emerged from the TV set.
Present are a group of young people wearing familiar items of clothing. One has a long multi-coloured scarf, others Cyberman and Meep T-shirts, and another a fez. They are Doctor Who fans. The Doctor and Belinda sit down and talk with them, learning that their favourite episode - unanimously - is Blink. They aren't too keen on Fifteenth Doctor episodes. They know about Belinda's parents, as she had described them to the Doctor on first arriving in Miami, and they have been watching. They think the ending to this episode has been signposted by the mention of highly flammable celluloid. They are unable to help any further as they are part of this fiction.
The Doctor and Belinda must once again break out of the picture.
They realise that the only way to achieve this is to break the film. They must stop it rolling through the projector, though the danger is that the bulb in the machine will cause the celluloid to burn, with them still trapped within the image.
They know they are back in the real cinema as the Doctor burned his hand slightly in escaping. He uses regeneration energy to heal it. Lux appears and is fascinated by this. The Doctor is full of light, which he can feed on. He believes the other Gods failed as they were saving the Doctor for him. He is captured by rolls of celluloid which writhe like snakes. Lux has seen footage of atom bomb explosions and wants to experience the light of the real thing. He will tap the Doctor's regeneration energy to build himself a corporeal body in order to escape into the outside world.
Remembering what the fans had said, Belinda decides to ignite the celluloid stock. The resulting explosion blows a hole in the wall, through which they see the sun rise. Lux is growing and becoming more solid.
The Doctor realises that the sun's energy will attract Lux towards it and away from the Earth, as no light source can compete with it.
He and Belinda run outside and meet Logan, and they see Lux grow to gigantic size before floating up into the air to dissipate into photons and merge with the sun.
The fifteen missing patrons emerge from the cinema and Renee is reunited with Tommy Lee, whilst the Doctor and Belinda slip away.
As people crowd round, a familiar figure pushes her way through to see what is going on. It is Mrs Flood.
Meanwhile, in a British living room, the group of fans realise they are still here. They are real...
Lux was written by Russell T Davies, and was first broadcast on Saturday 19th April, 2025.
It sees the introduction of the latest member of the pantheon of deities which have included the Toymaker and Maestro, who are glimpsed in flashbacks to The Giggle and The Devil's Chord. It's Belinda's first trip in the TARDIS and the latest story to have a historical setting - this time the near past of the 1950's.
The location is Miami, Florida, during the era of racial segregation and this is touched on in the script, obviously, as we have our first non white TARDIS team. It's mentioned first when the Doctor and Belinda go into the diner, but young Logan declines to enforce the law. The police officer later talks about the segregated nature of the cinema.
Of course, a black companion with a medical background had already questioned the practicalities of visiting historical eras when racism was more prominent - Martha Jones, in The Shakespeare Code. Then, the Doctor had pointed out that earlier societies have been far more tolerant and diverse than people think. Here, they are in a society where division is enshrined in law.
Once touched upon, this doesn't have any impact on the rest of the story, which is very much one about fiction and visual imagery - especially the language of film.
Mr Ring-a-Ding is simply the form which Lux, God of Light, has found himself in.
The Doctor and Belinda are transported onto celluloid, initially as animated characters themselves. This isn't exactly original - there's an episode of Supernatural, for instance, in which the main characters - Sam and Dean - become animated and meet Scooby Doo and his gang. (Here, the Doctor actually refers to himself and Belinda as Velma and Fred respectively).
Star Trek went the other way and had characters from Lower Decks appear in non 2-D form in an episode of Strange New Worlds.
Cartoon / live action interactions go back a very long way in cinema history. Remember Gene Kelly dancing with Jerry Mouse from the Tom & Jerry cartoons, for instance?
And let's not forget the Torchwood episode Out of the Rain, which centres around a cinema and features figures who exist on celluloid. Fear Her also had people trapped within images.
Talking of Supernatural, that series also featured Sam and Dean discovering that they existed within fan fiction, and their entire lives were being written as a series of novels by a deity.
The fans whom the Doctor and Belinda encounter are fairly stereotypical of the audience which RTD2 thinks is following the programme - the target audience which the BBC and Disney sought to capture. They are all of a similar age - '20's - and there's a mix of gender and ethnicity.
They are certainly not typical of the active fans of the programme - the ones who don't just watch the series but spend time and money to attend events. Whilst the gender mix is true of them, there is a much wider age range and they are still predominantly white affairs, at least as far as the UK is concerned in my experience.
The main guest artist this week is only heard, not seen. Voicing Mr Ring-a-Ding is Alan Cumming, who had previously played King James in The Witchfinders. In the US he is best known for hosting The Traitors these days, but first made his mark on Broadway and in movies such as Goldeneye and the first X-Men sequel. In the UK, an early TV role was in the Scottish crime drama Taggart, playing a teenager framed for murder. He is currently artistic director of the Pitlochry Festival Theatre, and is touring with a live show based on his airline sitcom The High Life.
Reg Pye is played by Linus Roache, who is the son of Coronation Street icon William Roache. He first came to notice in the film Priest (1994), starring opposite Robert Carlyle and Tom Wilkinson. In this he played a Roman Catholic priest struggling with his sexuality. TV appearances have included regular roles in Vikings and Law & Order: Special Victims Unit.
Diner worker Logan is played by Lewis Cornay. His work is primarily in musical theatre, including the title role in the The SpongeBob Musical. Currently in The Book of Mormon in the West End.
Renee Lowenstein is Lucy Thackeray. She's been in EastEnders and has appeared in Marvel's Moon Knight, and features in Jurassic Park Rebirth.
William Meredith, who plays the police officer, had previously appeared in Arachnids in the UK, where he played Jack Robertson's bodyguard Kevin.
Finally, Anita Dobson is back as Mrs Flood - appearing outside of a contemporary London setting for the first time. This forms part of this series' story arc.
Overall, it's a fun episode with an interesting new adversary - though one that would be difficult to ever bring back. Visually impressive, if not entirely original, it's still one of the better episodes of the Gatwa era. The appearance of the fans is one of those What?! moments.
Things you might like to know:
- Lux debuted with overnight viewing figures of only 1.58 million - the lowest in the programme's history and the first time ratings had dropped below 2 million.
- RTD2 claimed that he had wanted to do an episode that mixed animation and live action for some time, but never had the budget to carry it through successfully. He had considered an episode like this during his first tenure as showrunner, though it would have been a hologram rather than a properly animated figure due to cost.
- Alan Cumming recorded all of his dialogue before any filming had taken place, some of it in a sound studio in New York. Gatwa and Varada Sethu asked for these to be played in during filming of their scenes so that they could react to them in real time.
- They watched episodes of the original Scooby Doo series by way of preparing for their performances as animated versions of their characters.
- Some of the animators who worked on this story had previously contributed to Who Framed Roger Rabbit? - another example of mixing live action and animation.
- Previously the Doctor could heal with regeneration energy, though it meant shortening his life to do so. Now it is said to be a by-product of bi-generation. (Even though The Timeless Children had established that he was actually a self-healing immortal anyway).
- Amongst the items owned by the fans are K-9 and Dalek mugs, a cushion with a Weeping Angel on it, a Third Doctor sonic screwdriver and a poster of the Fifteenth Doctor and Ruby. They also have Doctor Who figurines and a Tenth Doctor Build-a-Bear. The actors playing the characters are all said to be real fans of the series.
- The Doctor points out to Belinda that humans are 60% water but can still drown - something he previously told Rose Tyler when using light to destroy another creature, in Tooth and Claw.
- The Palazzo Movie Theatre location is the art deco Penarth Pier Pavilion Cinema, should you ever wish to visit.
- There's a poster for a film called "Rocket to Venus" on the projection booth wall. Alan in The Robot Revolution had the same poster in his bedroom.
- Sadly, the director - Amanda Brotchie - died in December 2025. She also directed The Well, filmed with Lux as part of the same production block.





















