The Sea Devils
The Sea Devils is a six-part serial of the British science fiction television programme Doctor Who, first broadcast in weekly instalments on BBC One from 26 February to 1 April 1972.[1] The story, written by Malcolm Hulke and directed by Michael E. Briant, marks the debut of the Sea Devils, a species of prehistoric aquatic humanoids related to the Silurians, who emerge from hibernation beneath the English Channel with plans to reclaim the planet from humanity.[2][3] It also features the return of the Doctor's arch-enemy, the Master, who manipulates events from prison to incite a war between the Sea Devils and humans.[2] In the serial, the Third Doctor (Jon Pertwee) and his companion Jo Grant (Katy Manning) investigate a series of ship sinkings near a coastal prison where the Master (Roger Delgado) is held.[4] The Doctor discovers an ancient underwater base housing the Sea Devils, turtle-like reptilians with advanced technology, including energy weapons and submarines, who view humans as invaders on their ancestral world.[3] Attempting diplomacy to avert conflict, the Doctor negotiates with the Sea Devils' leader, but escalating tensions lead to attacks on naval vessels and a climactic assault on the base, which the Doctor destroys using a makeshift device to "reverse the polarity of the neutron flow."[3] The Master's scheme is thwarted, though he escapes, highlighting themes of misunderstanding and prejudice between species.[2] Produced during Jon Pertwee's tenure as the Third Doctor, The Sea Devils was the third serial of the ninth season, following The Curse of Peladon and preceding The Mutants. Notable for its underwater filming at a naval base and use of stock footage, the serial received mixed reviews upon release but has since been praised for its action sequences, including a fencing duel between the Doctor and the Master, and the Sea Devils' distinctive design by John Friedlander.[2] The monsters returned in the 1984 serial Warriors of the Deep and the 2022 special Legend of the Sea Devils, cementing their status as classic Doctor Who adversaries.[3]Synopsis
Plot summary
In the first episode, the Third Doctor and his companion Jo Grant visit the Master, who is imprisoned in a high-security facility on Fortress Island off the south coast of England. While there, the Doctor becomes concerned about a series of mysterious ship sinkings in the area, which the Navy attributes to natural causes or enemy action. Returning to the mainland, they investigate a naval base commanded by Captain Hart and Colonel Trenchard, where they examine a scorched lifeboat from one of the missing vessels. Meanwhile, the Master, collaborating with the Sea Devils—an aquatic race related to the Silurians—begins awakening their leader from hibernation in an underwater base, using stolen naval equipment to further his plans. A Sea Devil attacks and kills a radio operator during a distress call, and later assaults workers at a sea fort, while the Doctor and Jo's boat is destroyed by an explosion, leaving them stranded.[5] In the second episode, the Doctor and Jo reach the sea fort, where the Doctor encounters a Sea Devil patrolling the area; he injures it with a makeshift weapon, causing it to retreat. Building a transmitter to summon help, the Doctor deduces the creatures' involvement in the sinkings. The Master, disguised, infiltrates HMS Seaspite to steal more equipment, aided by the unwitting Trenchard, who believes him to be a government official. The Doctor and Jo return to the naval base, confronting Trenchard about the irregularities, but their suspicions lead to a tense standoff. The Master reveals himself during a sword duel with the Doctor aboard the ship, attempting to kill him with a thrown dagger, highlighting the Doctor's preference for negotiation over violence in contrast to the Master's manipulative tactics.[5] The third episode sees the Master narrowly missing the Doctor with his dagger, after which Trenchard, deceived by the Master's lies, imprisons the Doctor on suspicion of treason. Jo frees the Doctor, but they are soon recaptured as the Master summons a Sea Devil to the prison, demonstrating his control over the creatures. The Doctor and Jo escape into a minefield surrounding the island, trapped between the advancing Sea Devil, the Master's forces, and the deadly explosives, as the Master's alliance with the Sea Devils deepens his scheme to provoke conflict.[5] In the fourth episode, the Doctor uses his sonic screwdriver to detonate the mines, creating a barrier that repels the Sea Devils temporarily. A Sea Devil attacks and sinks a submarine, escalating the naval losses, while another vessel vanishes. The Master activates a communication device in the Sea Devils' base, rallying more of the creatures. He orchestrates an assault on the island prison, where Sea Devils kill the guards and Trenchard. The Doctor, attempting to reach the underwater base for diplomatic talks, descends in a diving bell but is captured upon arrival, underscoring his persistent efforts to broker peace despite the Master's sabotage. Jo, showing initiative, begins actively aiding the Doctor's plans.[5] The fifth episode unfolds in the Sea Devils' base, where the Doctor meets their leader and pleads for coexistence, but the Master incites the creatures to war by blaming humanity for past aggressions. Depth charges from a naval attack interrupt the negotiations, further alienating the Sea Devils. Convinced by the Master, they launch a mass uprising, emerging on land to attack the naval fort and other installations. The Doctor and Jo are imprisoned by the Sea Devils, but Jo's resourcefulness helps them escape, as the Doctor rescues the crew of a trapped submarine and uses its torpedoes to flee the base amid the growing chaos.[5] In the sixth and final episode, the Doctor employs Venusian karate to subdue a Sea Devil guard but is recaptured along with Jo. As the Sea Devils besiege the naval base, the Doctor constructs a device that emits a high-frequency sound to incapacitate the creatures en masse. The Master hypnotizes a soldier to aid his getaway, but the Doctor reprograms the Master's doomsday weapon to overload, causing a catastrophic explosion that destroys the Sea Devil base and thwarts the uprising. The Master escapes in the confusion using a decoy, leaving the Doctor to reflect on the fragile hope for future peace, while Jo emerges as a more confident participant in their adventures.[5]Allusions and references
The Master's manipulation of Colonel Trenchard alludes to the 1789 mutiny on HMS Bounty, paralleling the historical naval rebellion in which Fletcher Christian led the crew against Captain William Bligh; here, the Master manipulates the rigid naval officer Trenchard to incite rebellion against established authority, underscoring themes of betrayal and subversion within military hierarchies. The story's motifs of a mysterious submarine vanishing at sea and an advanced underwater base draw direct allusions to Jules Verne's 1870 novel 20,000 Leagues Under the Sea, where Captain Nemo's Nautilus explores hidden oceanic realms amid technological marvels and isolation; this connection enriches the narrative's exploration of humanity's fraught relationship with the deep, positioning the Sea Devils' domain as a similarly enigmatic, self-contained world threatening surface civilization. Writer Malcolm Hulke critiques militarism through this plot, portraying human aggression as the catalyst for interstellar conflict rather than diplomacy.[6]Production
Development and writing
"The Sea Devils" was commissioned in March 1971 by producer Barry Letts and script editor Terrance Dicks as the third serial for the ninth season of Doctor Who, specifically conceived as a sequel to the earlier story "Doctor Who and the Silurians" to revisit its reptilian antagonists in an aquatic setting.[7] Malcolm Hulke, who had previously created the Silurians, was selected as the writer due to his familiarity with the characters and his personal experience serving in the Royal Navy during World War II, which informed the maritime elements of the narrative.[7] Hulke submitted his initial scripts in May 1971, building on the environmental themes from his Silurian story by portraying the Sea Devils as an ancient species awakened by human activities disrupting their hibernation, such as the construction of sea forts.[8] The original working title was "The Sea Silurians," emphasizing the connection to the land-dwelling Silurians, but it was changed to "The Sea Devils" to better distinguish the aquatic variants and evoke a sense of menace, with significant input from Letts and Dicks who insisted on the return of the Master as a central antagonist to drive the plot while limiting his appearances to maintain dramatic tension.[7] Hulke was a longtime member of the Communist Party of Great Britain. During revisions, the script was adjusted to expand companion Jo Grant's role, incorporating more action sequences for her character to heighten the serial's adventure elements and provide contrast to the Doctor's diplomatic efforts.[8] The final structure was set at six episodes, each approximately 25 minutes long, to align with the season's broadcast schedule and allow for a balanced exploration of the themes without exceeding production constraints.[7]Casting
Jon Pertwee continued his portrayal of the Third Doctor, a role he had assumed since Spearhead from Space in 1970, bringing his established action-oriented style to the serial's physical confrontations.[5] Katy Manning reprised her role as companion Jo Grant, introduced in Terror of the Autons the previous year, with the script highlighting opportunities for her physical comedy, including stunts like abseiling down a sea fort rigging, which she performed herself alongside Pertwee.[9][5] Roger Delgado returned as the Master, marking the character's fourth appearance and reinforcing narrative continuity as the Doctor's persistent adversary following The Dæmons.[5] His reprise was integral to the season's arc, with no casting alternatives considered due to the established dynamic with Pertwee.[9] The serial introduced naval personnel to fill the absence of UNIT, with Edwin Richfield cast as the authoritative Captain Hart, commander of HMS Seaspite, and Clive Morton as the bumbling Colonel Trenchard, selected for his commanding yet comedic military presence in prior BBC productions.[9] Supporting roles included Hugh Futcher as the sailor Hickman and John Woodnutt as Lieutenant Commander Robbins, drawn from the BBC's pool of character actors experienced in ensemble military scenes.[9] The titular Sea Devils were depicted through a combination of costume and voice work, with Peter Forbes-Robertson portraying the Chief Sea Devil, whose leadership role required expressive physicality within the restrictive suits designed by Maggie Fletcher.[9] Additional Sea Devils were played by uncredited extras and stunt performers, including Pat Gorman and Stuart Fell, sourced from the BBC's regular roster to populate the underwater and attack sequences efficiently.[9] Behind-the-scenes notes reveal Pertwee's personal judo training informed the Doctor's Venusian karate maneuvers against the Sea Devils, adding authenticity to the fight choreography without necessitating stunt doubles for key moments.[5] Delgado's well-documented aquaphobia posed challenges during water-based filming but did not affect his casting or performance continuity.[10] No major recasts occurred, as the production adhered closely to the established ensemble for the 1971 filming schedule.[9]Filming and locations
Principal photography for The Sea Devils commenced in October 1971 and extended into November, with location filming primarily occurring between 21 and 29 October across southern England sites, followed by studio sessions at BBC Television Centre in London.[8][11] The production team recorded interiors in Studio TC8 at the Television Centre on 15–16 November, 29–30 November, and 13–14 December 1971, adhering to the standard fortnightly two-day blocks for the era, where director Michael E. Briant opted to tape one episode per studio day.[8][12] Exterior sequences were shot at key naval and coastal locations, including the Fraser Gunnery Range at HMS St George in Portsmouth for base and gunnery scenes on 21, 22, and 25 October, and aboard the diving support vessel HMS Reclaim on 26 October.[8][11] The production benefited significantly from Royal Navy cooperation, which provided access to facilities, equipment, and personnel, including marines who participated in the Episode Six battle sequences as part of a training exercise; this support helped portray the Navy positively while offsetting logistical costs.[8] Additional filming took place at No Man's Land Fort in the Solent on 26 October, and various Isle of Wight sites such as Whitecliff Bay and Red Cliff in Sandown on 27 October for Sea Devil emergence scenes, Bembridge Sailing Club and Priory Bay on 28 October, and Norris Castle in East Cowes on 29 October.[8][11] Underwater and aquatic elements, including submarine and diving bell sequences, were simulated through studio techniques rather than on-location dives, with model work and compositing employed for effects like the Sea Devils' underwater base.[8] Director Briant utilized chroma key (CSO) overlay for integrating these elements, particularly in scenes involving the model submarine that inadvertently resembled a classified Polaris design, prompting brief Ministry of Defence scrutiny.[8] The production faced several logistical challenges, including weather disruptions such as fog on 27 October that delayed the planned abseiling sequence at Whitecliff Bay, requiring rescheduling. The production faced additional challenges, including power outages that disrupted the broadcast of early episodes, and the model submarine briefly drawing Ministry of Defence attention for resembling a classified design. Actor injuries also impacted the schedule: Jon Pertwee bruised his ribs during a diving stunt onto his sonic screwdriver on 27 October, and Katy Manning cut her hands descending a rope too quickly on 29 October.[8] The Sea Devil costumes, featuring rigid fibreglass shells over blue netting to evoke scaly skin, limited actor mobility and contributed to pacing delays in action scenes, though the design allowed for more fluid movement than their Silurian predecessors.[8] The production's costs were elevated by extensive location work but mitigated through Navy assistance in providing resources at no cost and the decision to use electronic music from the BBC Radiophonic Workshop instead of a full orchestral score, avoiding additional composer fees.[8]Music and effects
The incidental music for The Sea Devils was composed by Malcolm Clarke at the BBC Radiophonic Workshop using the EMS Synthi 100 synthesizer, representing the first fully electronic soundtrack in the history of Doctor Who. This approach was adopted to offset budget overruns from extensive location filming, replacing the originally assigned composer John Baker.[8][13] Key musical cues featured pulsing, abrasive electronic themes underscoring the Sea Devils' menace and tense, oscillating motifs evoking submarine tension and underwater peril, all generated without traditional instrumentation to pioneer an experimental sonic palette for the series. Clarke's composition drew on musique concrète techniques, influenced by Workshop pioneer Delia Derbyshire, emphasizing manipulated electronic textures over melodic orchestration.[8][14] Sound effects were also crafted at the Radiophonic Workshop under Brian Hodgson, incorporating reverberant underwater echoes, guttural reptilian hisses, and modulated vocal processing to give the Sea Devils their distinctive, otherworldly timbre. These audio elements enhanced the serial's aquatic and alien atmosphere, integrating seamlessly with the electronic score.[15] Visual effects, overseen by designer Peter Day at the BBC Visual Effects Department, relied on practical models for the Sea Devils' doomsday device—a scaled prop simulating destructive energy beams—and chroma key (CSO) compositing to augment studio-built interiors of the underwater base, creating illusory depth and scale. These techniques complemented on-set logistics from naval location shoots, such as the diving bell sequences filmed at Portsmouth.[8]Broadcast and reception
Broadcast details
"The Sea Devils" was originally broadcast on BBC One from 26 February to 1 April 1972, airing in six weekly episodes on Saturdays at approximately 5:50 PM.[8] As the third serial of the ninth season, it followed "The Curse of Peladon" in the transmission order and occupied a pre-watershed timeslot aimed at a family audience.[8] Viewership figures for the serial varied across its run, peaking in the second episode before declining toward the finale. The episodes drew the following audiences:| Episode | Air Date | Viewers (millions) |
|---|---|---|
| 1 | 26 February 1972 | 6.4 |
| 2 | 4 March 1972 | 9.7 |
| 3 | 11 March 1972 | 8.3 |
| 4 | 18 March 1972 | 7.8 |
| 5 | 25 March 1972 | 8.3 |
| 6 | 1 April 1972 | 8.5 |