Kamelion is malfunctioning when the TARDIS picks up a distress signal emanating from modern-day Lanzarote. Archaeologist Howard Foster has found a strange artefact which is taken by his step-daughter, Peri Brown. When Turlough saves Peri from drowning and brings her aboard the TARDIS, the Doctor realises that the artefact is emitting the signal. It propels the TARDIS to the planet Sarn, where Kamelion falls under the sway of the Master, and convinces Chief Elder Timanov that he is a divine emissary. Meanwhile, Turlough finds evidence of a mysterious connection between Sarn and his homeworld of Trion.

Towards the end of 1982, a strike by the BBC electricians' union delayed the recording of Enlightenment for Doctor Who's twentieth season. Director Fiona Cumming took advantage of the unexpected time off to enjoy a trip to Lanzarote, the easternmost of Spain's Canary Islands off the coast of Morocco. When production on Enlightenment finally resumed, it was given the studio dates originally assigned to the intended season finale. This was “The Return”, which was to be directed by Peter Grimwade. Instead, it was eventually made by Matthew Robinson as part of Season Twenty-One, under the title Resurrection Of The Daleks. This sequence of events would prove to have repercussions for the story immediately following the rescheduled Dalek adventure.

First, during her trip to Lanzarote, Cumming sent a postcard to Doctor Who producer John Nathan-Turner, suggesting that he should consider the island as a potential filming location. Doctor Who had spent several days in Amsterdam for 1983's Arc Of Infinity, and Nathan-Turner was now keen for Doctor Who to go abroad at least once per season. Upon further investigation, he was delighted to discover that his budget would indeed permit a week in Lanzarote.

Eric Saward felt badly that Peter Grimwade's pre-production work on “The Return” had gone to waste

Meanwhile, script editor Eric Saward felt badly that Grimwade's pre-production work on “The Return” had gone to waste. A misunderstanding following the serial's cancellation had also led to discord between Grimwade and Nathan-Turner, which Saward felt was a result of an overreaction on the producer's part. Saward wanted to make things up to Grimwade, and offered him a scripting assignment for Season Twenty-One's fifth slot; he had most recently written 1983's Mawdryn Undead, which had introduced Turlough. Grimwade accepted, and a storyline called Planet Of Fire was commissioned on March 29th, 1983; the title “Planet Of Fear” may also have been considered.

In developing Planet Of Fire, Grimwade had to contend with a number of requirements, the most obvious being the use of the unfamiliar Lanzarote locale. To take advantage of the landscape's variety, Grimwade decided that Lanzarote would feature as two different locations in the story: the Greek island of Aeschyllos and the alien planet Sarn. However, he was subsequently informed that the deal worked out between the production office and the Lanzarote Tourist Board meant that the Earthbound sections would actually have to be set in Lanzarote itself. As a result, Grimwade had to abandon some of the historical detail he had worked out.

Grimwade would also have to account for a number of comings and goings amongst the TARDIS crew. All three members of the regular cast -- Peter Davison, Mark Strickson and Janet Fielding -- had decided to leave Doctor Who during Season Twenty-One. Nathan-Turner and Saward had decided to scatter these departures throughout the season. Tegan would be written out at the end of story four, Resurrection Of The Daleks, while the Doctor would regenerate in story six, The Caves Of Androzani. Since his serial would fall in between, Grimwade was tasked with providing an exit for Turlough. This would permit him to draw upon the deeper background for the character -- including a previously unused first name, Vizlor -- which he had developed when writing Mawdryn Undead.

Turlough was not the only TARDIS traveller making an exit in Grimwade's narrative. Kamelion, the robot companion introduced in The King's Demons at the end of Season Twenty, had never worked as intended, and the situation had been made worse by the accidental death of one of the prop's developers. As a result, Kamelion's second appearance would also be his last. Grimwade would have to ensure that his storyline was structured to avoid bringing the physical robot on location, due to the number of people required to operate it. Balancing these departures would be the introduction of a new companion, Perpugilliam “Peri” Brown, who had been created by Nathan-Turner and Saward during February 1983. Finally, Grimwade's adventure would bring back the Master for his annual contretemps with the Doctor. Anthony Ainley's contract to play the Master was about to expire, so Grimwade was asked to write the character out in a potentially permanent way.

Peri was meant to bond with the Doctor in part because he reminded her of her late father

Full scripts for Planet Of Fire were commissioned on April 20th. A particular struggle for Grimwade was Peri Brown, and he had to work closely with Saward to establish a strong characterisation which did not lean on American cliches. Some elements of her background were dropped as the writing progressed, including the notion that she bonded with the Doctor in part because he reminded her of her late father, who had died at the same age the Doctor now appeared to be. Peri had also been envisaged as wealthy and blonde; the latter was abandoned with the casting of brunette Nicola Bryant during the summer. Another source of unhappiness for Grimwade was Saward's decision to tone down the story's commentary on issues of religious zealotry, which the writer felt was unnecessarily cautious.

The obvious choice to direct Planet Of Fire was Cumming, who was delighted when veteran actor Peter Wyngarde accepted her invitation to play Timonov. However, Wyngarde then seized upon the script's implication that the numismaton gases had greatly prolonged Timonov's life, and made worrisome suggestions about the character speaking and moving very slowly. Fortunately, he later changed his mind and decided to interpret Timonov as being in the mould of World War One hero TE Lawrence, as played by Peter O'Toole in the 1962 movie epic Lawrence Of Arabia. Meanwhile, Grimwade was frustrated by Cumming's decision to cast Dallas Adams as Howard Foster. The character had been conceived as an older man who evoked the spirit of archaeologist Howard Carter -- the discoverer of the tomb of Tutankhamun -- but this was now lost.

Cumming and her team travelled to Lanzarote on October 13th, to prepare for the start of filming the next day. Work on the 14th took place at Playa del Papagayo, at the southern tip of the island, for the scenes on the research boat and the beach. Bryant's first day of recording on Doctor Who was disrupted in bizarre fashion when she was “rescued” by a German nudist, who believed that Bryant was actually drowning when she filmed the scene of Peri in the water. The man was very unhappy to learn that Bryant was just acting, and later ruined a take for a scene on the beach by running through the shot.

October 15th took cast and crew to the northern edge of Lanzarote, where the observation point of Mirador del Rio posed as Malkon's quarters. The day concluded a couple of miles to the east, when material at the jetty and in the cafe was filmed at Órzola. After a break on October 16th, the final three days -- from the 17th to the 19th -- saw recording shift to the Parque Nacional de Timanfaya, in western Lanzarote. There, the Montañas del Fuego offered venues suitable for various parts of the Sarn landscape. On the last night in Lanzarote, Adams and Wyngarde liberated some turtles kept in the hotel pool and released them into the sea, causing the police to be summoned.

The first studio block for Planet Of Fire took place on October 26th and 27th at BBC Television Centre Studio 1 in White City, London. The first day dealt with scenes in the Unbelievers' bunker and the adjacent tunnel, as well as the colonnade outside the Hall of Fire. Cumming also started work on some of the material within the Hall itself, which she completed on the second day. On October 31st, Kamelion's dialogue was read by Gerald Flood, who had previously played the robot in The King's Demons.

Work on Planet Of Fire resumed in TC6, from November 9th to 11th. The first day concentrated on sequences in the Doctor's TARDIS and the seismic control centre. The script provided no last word for the Master's final plea to the Doctor, prompting Cumming to seek clarification from Nathan-Turner. The producer suggested that the Master would have described himself as the Doctor's “own brother”. The middle day focussed on material in the Master's laboratory and the Trion spaceship. This left scenes in the Sarn ruins and the Master's TARDIS to the final day, alongside various effects shots. Although November 11th ostensibly marked the end of Strickson's time on Doctor Who, he would in fact make a brief return in the very next story, The Caves Of Androzani.

Doctor Who returned to its usual Thursday and Friday timeslots for Planet Of Fire, after Resurrection Of The Daleks had been shifted to Wednesdays during the broadcast of the 1984 Winter Olympics. The BBC's Friday evening schedule continued to undergo some variation, with Episode Two leading into Junior Superstars on February 24th, while the concluding installment was followed by the main The Superstars competition on March 2nd. Although it was expected that Cumming would return to Doctor Who for its 1986 season, Planet Of Fire wound up being her final directing assignment on the show. It was also Grimwade's last contribution to Doctor Who, as his personal issues with Nathan-Turner and his unhappiness with the development of Planet Of Fire left him disillusioned with the programme.

• Doctor Who Magazine #206, 24th November 1993, “Archive: Planet Of Fire” by Andrew Pixley, Marvel Comics UK Ltd.
• Doctor Who Magazine Special Edition #1, 2001, “Hide And Seek” by Andrew Pixley, Panini Publishing Ltd.
• Doctor Who: The Complete History #39, 2018, “Story 134: Planet Of Fire”, edited by Mark Wright, Hachette Partworks Ltd.
• Doctor Who: The Eighties by David J Howe, Mark Stammers and Stephen James Walker (1996), Virgin Publishing.
• Doctor Who: The Handbook: The Fifth Doctor by David J Howe and Stephen James Walker (1995), Virgin Publishing.
• In·Vision #75, November 1997, “Production” edited by Anthony Brown, Cybermark Services.