In a cave complex on twenty-sixth-century Earth, the Doctor, Adric, Nyssa and Tegan come to the aid of a platoon of soldiers, who have been attacked while investigating the deaths of several scientists. The Doctor discovers that the killers are actually androids, left to guard a massive bomb capable of destroying the planet. The Doctor disarms the explosive with Adric's help. He traces the detonation signal to a deep-space freighter where recent disappearances amongst the crew have baffled Captain Briggs. The true culprits are the Cybermen, whose plot against the Earth will have devastating consequences...

Adric had to die. That was the conclusion reached by Doctor Who producer John Nathan-Turner in early 1981. The character had never quite come together as intended, disappointing Nathan-Turner and frustrating actor Matthew Waterhouse, who was also a sometimes awkward presence on set. Furthermore, it had become clear that writers were struggling to provide adequate material for all three of the companions who would be travelling with Peter Davison's Fifth Doctor. However, Nathan-Turner felt that Adric did not lend himself to a traditional departure scenario, and this prompted the decision that he should be killed off. Not only would this accrue a lot of publicity for Doctor Who -- no regular character had exited the programme in such a manner since short-lived companions Katarina and Sara Kingdom in 1965's The Daleks' Master Plan -- but Nathan-Turner also thought that it would imbue the show with a greater sense of danger and tension, while making the surviving characters seem much more vulnerable than had previously been the case.

The story earmarked for Adric's demise was “The Enemy Within” by science-fiction author Christopher Priest, which was intended to be the penultimate adventure of Season Nineteen. In mid-June, however, a serious disagreement arose between Priest and Nathan-Turner over payments for rewrites. Following a venomous telephone conversation, it became clear that “The Enemy Within” would have to dropped from the schedule. With production due to begin in just four months, it was agreed that a replacement would be written by script editor Eric Saward.

Permission was sought for Eric Saward to write Earthshock in the gap after the expiry of his interim contract

At this time, Saward was nearing the end of a three-month appointment which was intended to bridge the absence of Antony Root, who was on a trainee posting with Juliet Bravo. It was now known that Root would not be returning to Doctor Who, however, and Saward agreed to accept the job on a permanent basis. Under BBC regulations, this meant that he would be forbidden from writing new Doctor Who serials. However, there would technically be a gap between the expiry of Saward's interim contract and the start of his ongoing position. As such, on June 29th, permission was sought for Saward to write a serial called “Sentinel” during this intervening period. It was granted on July 24th, and his commission came the same day. To further avoid any appearance of impropriety, Root agreed to perform minor work on “Sentinel” so that he could be credited as the script editor.

Both Saward and Davison were fans of the Cybermen, who had made five appearances in Doctor Who during the Sixties, but had subsequently been seen only in 1975's Revenge Of The Cybermen. Urged on by fan adviser Ian Levine, Nathan-Turner was eager to bring back popular monsters from the series' past, and he readily agreed to the return of the Cybermen in “Sentinel”. Tired of Doctor Who monsters always being killed off in their first appearance, Saward considered having the Cyber Leader survive “Sentinel” -- providing yet another sign of the Fifth Doctor's fallibility in comparison to his predecessor -- but eventually decided against it.

Although some consideration was given to ending “Sentinel” with the revelation that Adric had escaped death, the production team ultimately stuck to their original plan for the character. It fell to Nathan-Turner to inform Waterhouse of Adric's fate. The young actor was initially appalled by the decision, and he refused to speak to his producer for two weeks. He was particularly upset that he would now be precluded from returning to Doctor Who at a later date. Eventually, Waterhouse was mollified by Nathan-Turner's observation that the Doctor could still encounter Adric at a time prior to his demise.

Earthshock would try, as much as possible, to capture the fast-paced feel of a feature film

During October, “Sentinel” was retitled Earthshock. Its director would be Peter Grimwade, who had just completed Kinda. Grimwade, Saward and Nathan-Turner were all keen that Earthshock should try, as much as possible, to capture the fast-paced feel of a feature film. As a result, Grimwade's final camera scripts were extremely lengthy, with Episode Four alone running to eighty-nine scenes -- far more than was normal for Doctor Who at that time.

Costume designer Dinah Collin was assigned the task of bringing the Cybermen into the Eighties, and worked on the project with Richard Gregory of effects firm Imagineering, based in Witney, Oxfordshire. They decided to abandon the rubber diving suits which had previously been the basis of the Cyberman outfit, opting instead for the more high-tech look of military g-suits. At Nathan-Turner's suggestion, the chins of the updated Cybermen were left clear so that the actors' jaws could be seen; the producer felt that this would reinforce the notion that the Cybermen had once been human. In a similar vein, Collin and Gregory considered leaving the Cybermen's hands bare -- as had been the case in their first appearance, in 1966's The Tenth Planet -- and then seamlessly integrating the flesh with the cybernetic arm. However, it was ultimately decided that this effect would be too complex to achieve. Collin also wanted to do away with the “handlebars” on the sides of the Cyberman helmets, but this was vetoed by Nathan-Turner and Saward, who felt that they were an essential part of the Cyberman image.

Work on Earthshock began on October 29th, when material at the mouth of the caverns was filmed at Springwell Quarry in Rickmansworth, Hertfordshire. Studio recording was then comprised of two three-day sessions at BBC Television Centre Studio 8 in White City, London. The first block took place from November 10th to 12th. The opening day dealt with most of the TARDIS interior scenes. Material in the main cavern and the various tunnels was the focus on the second day, together with some of the sequences in the small cavern where the TARDIS materialised. These were completed on the last day, along with the awakening of the dormant Cybermen and the climactic TARDIS scenes.

Also recorded on November 12th was all of the action in Cyber Control, which incorporated a series of flashbacks to older Doctor Who stories. Nathan-Turner had been delighted by the reception of a similar sequence in the concluding episode of Logopolis the previous year, and so he was alert for opportunities to include more such moments. Earthshock was an obvious candidate, and Saward and Levine worked together to select one clip for each Doctor who had previously encountered the Cybermen. They settled on extracts from The Tenth Planet (the First Doctor), The Wheel In Space (the Second Doctor) and Revenge Of The Cybermen (the Fourth Doctor).

The second studio block spanned November 24th to 26th, and included all of the scenes aboard the freighter. Action on the bridge and in various corridors was recorded on all three days, together with events in the hold on all but the 24th. The middle day also saw Grimwade tape material on the stairs, and modelwork was completed on the final studio day. The miniature freighter included elements which were an intentional homage to the Nostromo from the 1979 movie Alien. Although Adric's death was amongst the material completed on the 26th, Waterhouse's time on Doctor Who was not yet over: the actor was still required to appear as an ersatz Adric in the season's concluding serial, Time-Flight.

The Radio Times offered a cover to promote the return of the Cybermen, but John Nathan-Turner was keen to keep their appearance a secret

In post-production, Grimwade became very unhappy with the incidental music composed by Malcolm Clarke of the BBC Radiophonic Workshop, which largely relied on natural metallic sounds such as hammers striking girders. The director complained to Nathan-Turner but, because there was no time to compose a new score, Clarke's work was retained. Meanwhile, the BBC's listings magazine Radio Times offered Nathan-Turner a cover to promote the return of the Cybermen. Doctor Who had not enjoyed such prominent publicity since 1973, but the producer was keen to keep the monsters' appearance a secret and declined the invitation.

When Earthshock Episode Four aired on March 16th, 1982, it concluded with the credits running silently over a shot of Adric's shattered badge for mathematical excellence. Nathan-Turner had borrowed this idea from a May 1964 broadcast of the soap opera Coronation Street, which had witnessed the death of original character Martha Longhurst. It marked the first occasion in the programme's history of a Doctor Who episode ending without the traditional theme tune.

• Doctor Who Magazine #239, 5th June 1996, “Archive: Earthshock” by Andrew Pixley, Marvel Comics UK Ltd.
• Doctor Who Magazine Special Edition #1, 2001, “Prince Charming” by Andrew Pixley, Panini Publishing Ltd.
• Doctor Who: The Complete History #35, 2018, “Story 121: Black Orchid”, edited by John Ainsworth, 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 #60, September 1995, “Production” edited by Anthony Brown, Cybermark Services.