Lux (Doctor Who)

314 – "Lux"
Doctor Who episode
Promotional title-card
Cast
Doctor Ncuti Gatwa – Fifteenth Doctor
Companion Varada Sethu – Belinda Chandra
Others Ian Shaw – Newsreader Cassius Hackforth – Tommy Lee Ryan Speakman – Husband Linus Roache – Reginald Pye Alan Cumming – Mr Ring-a-Ding Millie O'Connell – Sunshine Sally Lewis Cornay – Logan Cheever Lucy Thackeray – Renée Lowenstein Jane Hancock – Helen Pye William Meredith – Policeman Samir Arrian – Hassan Chowdry Bronté Barbé – Lizzie Abel Steph Lacey – Robyn Gossage Anita Dobson – Mrs Flood
Production
Directed by	Amanda Brotchie
Written by	Russell T Davies
Script editor	David Cheung
Produced by	Chris May
Executive producer(s)	Russell T Davies Julie Gardner Jane Tranter Joel Collins Phil Collinson
Music by	Murray Gold
Series	Series 15
Running time	43 minutes
First broadcast	19 April 2025 (2025-04-19)
Chronology
← Preceded by "The Robot Revolution" Followed by → "The Well"

"Lux" is the second episode of the fifteenth series of the British science-fiction television series Doctor Who. It was written by Russell T Davies, the Doctor Who showrunner, from a concept first developed over two decades prior, and directed by Amanda Brotchie.

In the episode, the Fifteenth Doctor (Ncuti Gatwa) and his companion, Belinda Chandra, land in 1952 Miami, Florida, while trying to make their way back to 2025. After doing so, they discover a mysterious cinema where fifteen people have disappeared. The pair stay to investigate and ultimately confront an animated God, Lux (voiced by Alan Cumming), who traps them in film.

"Lux" is unusual for the programme in that it features a mixed live-action and animated format. Filming for the episode took place in Penarth, Cardiff and at Wolf Studios Wales in January 2024. Some voice-over work took place internationally in New York City in June. Animation and other post-production work continued later into the year, with some tasks still being completed as late as September.

The episode includes references to popular culture, fourth wall breaks and meta-references to its own fan base. It was released on BBC iPlayer, BBC One, and Disney+ on 19 April 2025. Reception to the episode was highly positive, with critics praising its use of animation in a live-action setting. A novelisation written by James Goss is set to be released in July 2025.

Plot

Unable to return to 24 May 2025, the TARDIS lands in 1952 Miami, where the Doctor and Belinda find a cinema that is chained shut. At a diner, they speak to the mother of one of fifteen people who disappeared from the cinema, which continues to play movies at night. Although racial segregation is still enforced, the waiter allows them to stay.

Inside the cinema, the pair discover a living cartoon, Mr Ring-a-Ding, the embodiment of Lux Imperator, God of Light, is responsible. The projectionist, Reginald Pye, plays films for Lux, who uses his power to recreate Pye's dead wife. Lux has trapped the missing people in a film reel. He similarly traps the Doctor and Belinda, and turns them into cartoon characters, until they regain their usual forms. They flee to another false reality, where a racist NYPD cop challenges them. They escape through a television watched by Doctor Who fans. Though delighted to meet the Doctor they reveal that their world that is the false one, and encourage him to return and defeat Lux, even though they will then cease to exist.

Back in the cinema, the Doctor heals his injured hand using residual regeneration energy. Lux steals the energy to create a solid body. Belinda attempts to burn film reels to cause an explosion, but encouraged by his wife, Pye sacrifices himself. The explosion exposes the cinema to sunlight causing Lux to expand infinitely until he becomes one with the universe. The missing people return.

As the Doctor and Belinda leave, Mrs Flood encourages the bystanders to watch the TARDIS dematerialise, claiming this "show" is a "limited run" that ends on 24 May. The Doctor's fans critique the episode, realising that they still exist.

Production

Development and production design

"Lux" was written by Russell T Davies. He had wanted to do an episode that included a living cartoon for a long time, but was unable to do one until now for funding reasons. He also revealed that he had considered variants of such an episode, including one two decades prior that would have featured a hologram rather than a legitimate animation as a result of the budgetary constraints. The story also contains mentions of segregation and racism in which Davies said he added to address issues in present-day society. It was also used as a subversion to the Doctor usually situating themselves as the main authority figure. While including such themes, he didn't want it to be the dominant subject. Among these are the NYPD officer saying the cinema is a space "reserved for white folk" and prejudicely assuming that Belinda is Caribbean. Other motifs present explore grief, hope, friendship, and sadness. Popular culture references to Rock Hudson and the Scooby Doo character Velma were included. Additionally, Davies has continued a recent trend of breaking the fourth wall. Also unusual for the show, the episode featured a mid-credits scene.

Costume designer Pam Downe created the Doctor's and Belinda's outfits using the complimentary colours of blue and yellow. Sethu's dress was inspired by a similar one worn by Anita (Ariana DeBose) and designed by Paul Tazewell in the 2021 adaptation of West Side Story. Meanwhile, Gatwa's blue suit was influenced by American musical artists of the 1950s. These hues were intended to further contrast with the red interior of the cinema by ultimately using all three primary colours. Downe ultimately wanted to successfully convey movement during the episodes action scenes. As such, three different wigs were considered for Sethu to wear and her dress had multiple underskirts.

The concept of Mr. Ring-a-Ding was inspired by animations from Fleischer Studios.

Ian Spendloff worked as a creative designer for the episode, and was the designer of Mr. Ring-a-Ding. Davies compared the concept of Mr. Ring-a-Ding to Fleischer animations from the 1930s. Spendloff drafted thirty different sketches that were considered before finally settling on the one used in the episode. Each one featured variations in noses, hair, and other elements. Mr. Ring-a-Ding was ultimately given a pig-like nose and blue skin to reflect characteristics of cartoon characters from the time period, with Davies wanting the character to look vaguely human but not be immediately identifiable as something else.

Meta-references to Doctor Who fans were also present in the episode because Davies recalled his enjoyment of cartoons while writing it, which made him consider people who loved the programme. Within the episode, the fans wore Doctor Who apparel (including a Fourth Doctor scarf, another a Cyberman "Telos" sweatshirt) and declared "Blink" (2008) as their favourite episode. One of them also mentioned the impending cancellation of the show. They then point out the "obviousness" of the episode's foreshadowing, and to online leaks. The show's BBC ident appears on the screen of their television. Although they say they are too inconsequential to be given surnames, all three characters—Hassan Chowdry, Lizzie Abel and Robyn Gossage—are fully named in the credits.

The concept of Doctor Who existing within its own universe had previously been briefly explored in Remembrance of the Daleks (1988) and other expanded media. Following this instance, such an idea was considered quasi-canon. This scene raised suspicion that Davies had potentially been planting spoilers online himself regarding upcoming episodes as well as rumours that the series would enter into another hiatus. When the fact that the episode was written and filmed well before the leaks began appearing was considered, it was compared to the futuristic predictions commonly seen in The Simpsons.

Casting

The episode stars Ncuti Gatwa as the fifteenth incarnation of The Doctor and Varada Sethu as his companion, Belinda Chandra. Alan Cumming voices the antagonist, Mr. Ring-a-Ding. It marks Cumming's second appearance in the show after his role as King James VI and I in the 2018 episode "The Witchfinders". Davies said that he and the production team had considered whether it was too soon to cast Cumming again and that had it been a live action role, he likely would not have been. Mr. Ring-a-Ding is the "God of Light" and part of the "Pantheon of Gods" that Davies has been developing since "The Giggle" (2023). Linus Roache stars as Reginald Pye, the theatre's projectionist and Lewis Cornay plays a diner worker who helps the Doctor and Belinda investigate the disappearances. Anita Dobson also makes a brief appearance as recurring character Mrs. Flood. The trio of fans were portrayed by Samir Arrian, Bronte Barbe, and Steph Lacey.

Filming and post-production

Exterior shots for the theater were filmed at Penarth Pier Pavilion. The wooden ramp can be seen at the bottom of the photo.

The story was filmed in the series' third production block, along with the following episode, "The Well". It was directed by Amanda Brotchie and recorded in late-January 2024. Location shooting took place in Penarth, Cardiff. The surrounding area was made up to look like an American city in the 1950s by adding vehicles and American flags. Penarth Pier pavilion was used for exterior shots of the theatre. The production team painted the building, added a period theatre sign, and removed a modern ramp at the front of the building. Its removal led to the discovery of rotting wood that had to be replaced at the show's expense. The episode was shot during Storm Jocelyn causing the cast and crew to struggle with unexpected rain and winds, requiring hot water bottles to keep warm during takes. Interior shots for the studio were filmed on soundstage 4 at Wolf Studios Wales. Pieces of that set were reused from "The Devil's Chord" (2024).

As a result of Mr. Ring-a-Ding being an animated creation, the performers had to interact with a two-foot acrylic cutout of the character or a thin green pole on set.The scenes were then edited during the post-production process. References for Mr. Ring-a-Ding's movement were filmed by crew, and then drawn directly into the scene by animators from Framestore. Cumming voiced his scenes in New York City on 28 June 2024. Elements of Cumming's facial expressions during this recording for were incorporated into Mr. Ring-a-Ding. The scene where the Doctor and Belinda are turned into cartoons were first recorded on a green screen, in which Gatwa and Sethu had to portray the characters in a rigid and cartoon-like manner. The animators used this as a reference for interaction between the two characters when redrawing them as a cartoon. Animations were done at twenty-five frames a second, requiring twenty-five drawings for each second of screen time, or fewer if characters' movement was limited.

Foley artists recorded sound effects at Bang Post Production in Cardiff, Wales on 4 September 2024. The episode's soundtrack included two singles: "Roll Over Beethoven" by Chuck Berry, and the Marlena Shaw rendition of "California Soul". Despite the episode taking place in 1952, the tracks were not released until 1956 and 1969, respectively. Murray Gold, the show's composer, also included the song "The Sad Man With A Box", a piece that he originally composed for series 5.

Broadcast and reception

Professional ratings

Aggregate scores
Source	Rating
Rotten Tomatoes (Tomatometer)	100%
Rotten Tomatoes (Average Score)	7.70/10
Review scores
Source	Rating
The A.V. Club	B
Bleeding Cool	10/10
The Daily Telegraph
Evening Standard
GamesRadar+
IGN	9/10
Radio Times
Vulture

Broadcast

"Lux" was simultaneously released on BBC iPlayer at 8 a.m. British Summer Time (BST) in the United Kingdom and on Disney+ in the United States at 12 a.m. Pacific Daylight Time on 12 April 2025. A BBC One broadcast followed at 7:15 p.m. BST. Disney also handled international distribution of the episode.

Ratings

The episode received overnight viewing figures of 1.58 million, the lowest broadcast ratings in Doctor Who's history. It was the fourth most-watched programme of the day on BBC One, with one show on ITV1 also achieving higher numbers.

Critical reception

On the review aggregator website Rotten Tomatoes, 100% of 10 critics' reviews are positive, with an average rating of 7.70/10. Robert Anderson, writing for IGN, praised the episode, highlighting Mr. Ring-a-Ding, several individual scenes, such as the fourth-wall-breaking scene, and the performances of Gatwa and Sethu. The Guardian's Martin Belam responded positively to the episode, praising Cumming's performance and the fourth-wall-breaking scene. Will Salmon, writing for GamesRadar+, highlighted Mr. Ring-a-Ding and Gatwa's performance, though felt Murray Gold's musical score "drowned out" some scenes. Adi Tantimedh, writing for Bleeding Cool, found the episode to be the strongest out of the episodes headed by Davies in his second tenure as showrunner.

Andrew Blair, writing for Den of Geek, highlighted the characterization of Mr. Ring-a-Ding, but criticized the episode's similarities to "The Devil's Chord", which he felt made the episode feel repetitive and weaker than it should have. He also felt the episode's handling of race was not effective, as while he felt the episode's inclusion of the topic was commendable, he felt the Doctor's in-universe way of handling it "can't help but scrape awkwardly against our real-world knowledge." Vicky Jessop, writing for the Evening Standard, criticized the inclusion of the scene featuring Doctor Who fans, stating that while it was initially entertaining, it quickly became "strained".

In print

Lux

Author	James Goss
Series	Doctor Who book: Target novelisations
Publisher	BBC Books
Publication date	10 July 2025
Pages	192
ISBN	9781785949555

A novelisation of the episode was written by James Goss and is due to be released on 10 July 2025 as part of the Target Collection.

External links

• "Lux" at BBC Online
• "Lux" at the Doctor Who Stories Website
• "Lux" on Tardis Wiki, the Doctor Who Wiki
• "Lux" at IMDb