Mutant Spiders rule the planet Metebelis Three in the far future, holding a regressive Earth colony in a grip of fear. The leader of the Spiders, the mammoth Great One, is constructing a device using Metebelis' powerful blue crystals which will increase her mental powers a millionfold. But the Doctor is in possession of the last crystal, and soon he and Sarah find themselves pursued by the Spiders and their human agents.

Roger Delgado had played the Master on Doctor Who since 1971, but during 1972 and 1973 made only occasional appearances in the programme. Despite this, he was discovering that many casting directors believed that he was still fully committed to Doctor Who, and were passing him over for work. As such, during the making of Frontier In Space -- Delgado's only story in Season Ten -- he and producer Barry Letts came to an agreement that the Master would be written out of Doctor Who in the final serial of the eleventh season.

To author the Master's swansong, the producer turned to Robert Sloman, who had written (with considerable input from Letts) the concluding stories of each of the last three seasons, most recently The Green Death. Sloman was beginning to tire of Doctor Who but acquiesced, and on February 15th, 1973 accepted a commission for a storyline entitled “The Final Game”. Drawing on Letts' proclivity for Eastern philosophy and the feature film Forbidden Planet, “The Final Game” would have revealed the Doctor and the Master to be two facets of the same person, with the Master as the “id” (instinctual needs and desires) and the Doctor as the “ego” (conscious perception of and adaptation to reality). At the adventure's climax, the Master would have perished in an explosion, in the process saving the Doctor and others from death -- although it would have remained ambiguous as to whether or not this was an act of redemption.

Unfortunately, “The Final Game” had to be abandoned in the wake of the events of June 18th, when Delgado died in a car accident in Turkey. This precipitated the final dissolution of the team which had carried Doctor Who through the Seventies, as it appeared that Letts, script editor Terrance Dicks, and star Jon Pertwee would all leave Doctor Who following Season Eleven. A reluctant Sloman was therefore asked to deliver a new storyline under his original commission, which would bring the era of the Third Doctor to a close.

Working with Letts, it was decided to again draw on Eastern notions by developing a story in which the Doctor confronts his destructive and rapacious thirst for knowledge. Letts also wanted to reward Pertwee -- who loved gadgets and vehicles of all kinds -- with an extended chase scene (which would end up forming the bulk of episode two). This was also an opportunity to wrap up the Metebelis Three subplot which had lightly run through Season Ten. Originally called “The Planet Of The Spiders”, the title was shortened to simply Planet Of The Spiders by the time the scripts were commissioned on December 5th. This was Sloman's last television credit; although the writer submitted one further storyline the following November, it was not accepted and Sloman thereafter confined himself to work in the newspaper industry.

Letts' agreement with the BBC permitted him to direct one story every recording block if he so chose; he had last helmed Carnival Of Monsters, and now opted to direct Planet Of The Spiders. Work began on Serial ZZZ with an experimental effects day at BBC Television Centre on February 22nd, 1974 before moving out on location for five days between March 11th and 15th.

The 11th was spent at three locations in Berkshire: Tidmarsh Manor at Tidmarsh was K'anpo's monastery, Mortimer Railway Station at Stratfield Mortimer was the train station, and rural road scenes were completed on nearby Bloomfieldhatch Lane. The remainder of the filming schedule was for scenes comprising part two's lengthy chase sequence. March 12th took cast and crew to Membury Airfield in Membury, Wiltshire. More material was filmed there on the 13th, as well as at Le Marchant Barracks in Devizes, Wiltshire. Finally, the 14th and 15th saw a relocation to the River Severn near Westbury, Gloucestershire.

Planet Of The Spiders followed the usual Doctor Who studio recording pattern of taping in fortnightly two-day blocks, this time on Tuesdays and Wednesdays. The first session occurred on April 2nd and 3rd in BBC Television Centre Studio 1, and covered all the material from parts one and two. Also completed on the Tuesday were the scenes set in the Doctor's lab from episodes three and six; this included the regeneration scene, and marked Tom Baker's first day on set. Nicholas Courtney ad-libbed the Brigadier's closing line, “Well, here we go again.”

The second block, on April 16th and 17th in TC8, was devoted solely to Earthbound sequences from the final four installments. Kismet Delgado -- Roger Delgado's widow -- joined the cast at this stage, as one of the Spider voice artistes. These days brought Richard Franklin's time on Doctor Who to an end. Franklin's subsequent work was mainly in the theatre, although he did return to play Mike Yates in both The Five Doctors and Dimensions In Time. Franklin also wrote the comedic stage play Recall UNIT: The Great Tea Bag Mystery, and penned a novel about Yates entitled The Killing Stone which did not see publication.

Recording on Planet Of The Spiders concluded on April 30th and May 1st in TC6, involving all the Metebelis Three scenes. Although this completed Season Eleven, the production block would continue with Tom Baker's first story, Robot. Unfortunately, Letts faced several difficulties in editing. First, the original cut of episode three was too short, and so material was inserted which had originally been intended for part four. This and other cuts created a domino effect, with Letts having to pull material back from episodes five and six. In addition to reprising the episode five cliffhanger several minutes into the final installment, the situation also forced Letts to include the Cave of Crystal flashback in episode six in order to ensure it had a sufficient running time.

Part six of Planet Of The Spiders aired on June 8th, bringing to a close far more than just Season Eleven. It was also Terrance Dicks' final credit as script editor. Dicks thereafter returned to freelance writing, although he also produced some classics serials in the mid-Eighties. Dicks maintained a very close connection with Doctor Who, providing several scripts for the programme. Additionally, Dicks became the primary contributor to Target Books' range of Doctor Who novelisations. Following the cessation of that line, he continued to scribe original Doctor Who novels for both Virgin Publishing and BBC Books, including Timewyrm: Exodus, Blood Harvest, The Eight Doctors and Deadly Reunion (cowritten with Letts). Dicks also wrote the stage play Doctor Who: The Ultimate Adventure, and was a candidate to script what would eventually become the TV movie Doctor Who (1996).

Most significantly, however, Planet Of The Spiders brought Jon Pertwee's successful five-year stint as the Doctor to its culmination. Pertwee continued to make appearances in film, on stage and on radio, including regular roles as the host of the game show Whodunnit? and as the title character in the children's programme Worzel Gummidge. His involvement with Doctor Who never flagged, as Pertwee became a fixture on the convention scene in the Eighties and early Nineties. He also returned to the programme on multiple occasions: in the televised anniversary specials The Five Doctors and Dimensions In Time, the stage show Doctor Who: The Ultimate Adventure, and the radio plays The Paradise Of Death and The Ghosts Of N-Space. Recordings of Pertwee were even used posthumously in the Big Finish Productions audio adventure Zagreus. Sadly, Jon Pertwee died of a heart attack on May 20th, 1996.

• Doctor Who: The Handbook: The Third Doctor by David J Howe and Stephen James Walker (1996), Virgin Publishing, ISBN 0 426 20486 7.
• Doctor Who: The Seventies by David J Howe, Mark Stammers and Stephen James Walker (1994), Virgin Publishing, ISBN 1 85227 444 1.
• Doctor Who Magazine #314, 6th March 2002, “Archive: Planet Of The Spiders” by Andrew Pixley, Panini Publishing Ltd.
• Doctor Who Magazine Special Edition #2, 5th September 2002, “The Show Must Go On” by Andrew Pixley, Panini Publishing Ltd.