An Earth colony in the far future has all the look and feel of a holiday camp. Immediately after arriving, however, the TARDIS crew is confronted by a disturbed man named Medok. He warns them of monsters which have secretly infiltrated the colony, even as the Pilot dismisses his claims, insisting that there is no such thing as Macra. The Doctor believes Medok and begins to investigate, so the colony's mysterious Commander orders the time travellers to be brainwashed. While the Doctor is able to save Polly and Jamie, he is too late to prevent Ben from being turned against his friends...

In early 1966, Ian Stuart Black wrote back-to-back stories for Doctor Who's third season: The Savages and The War Machines. In November of the same year, story editor Gerry Davis asked Black to submit a new idea, indicating that he wanted a holiday camp setting involving monsters living under the ground. Both Black and Davis were keen to avoid reusing old concepts and, after reviewing the roster of Doctor Who serials to date, they settled on an arachnid creature as something the programme had not yet attempted. Black was duly commissioned to write “The Spidermen” on December 11th. The title would acquire an exclamation mark later in the month. It appears that Black's serial was briefly a contender to be the sixth story of Season Four (and hence the fourth adventure for Patrick Troughton's Second Doctor) but it was soon pencilled into the subsequent slot.

Black's original drafts differed from the finished scripts in a few respects. Most notably, in Episode Two, the Doctor was originally sent to the “House of” (rather than “Hospital for”) Correction alongside Medok, and it was after the failure of the brainwashing attempts there that he was sent to the pithead. The Pilot at this stage was referred to as the Prime Minister, and Medok was spelt “Medoc”. Black deviated from the original arachnid vision of the monsters, describing them as general insectoid creatures, and the serial's title became “The Insect-Men” to reflect this. However, Davis feared that the result might hew too closely to the Zarbi from 1965's The Web Planet, and decided that the monsters should instead be giant crabs. They were thus dubbed Macras, apparently from the genus name of the Japanese spider crab, macrocheira kaempferi. Unfortunately, some dialogue which referred to the Macra as “insects” survived in Black's final draft and were present upon transmission. The title was changed to “The Macras” and then, finally, to The Macra Terror in mid-January 1967.

It was now planned that Ben and Polly's exit would occur midway through The Evil Of The Daleks

Meanwhile, Anneke Wills was contracted for The Macra Terror and the ensuing eight episodes (intended to comprise two further four-part stories) on December 12th. In the weeks that followed, Davis and producer Innes Lloyd elected to write Polly and Ben out of Doctor Who, feeling that their characters were not working as well as they had hoped. Furthermore, on January 2nd, it was decided that The Macra Terror would be followed by the six-part The Faceless Ones, meaning that Wills' contract now expired with part two of the subsequent adventure, The Evil Of The Daleks. As such, Lloyd and Davis planned for Ben and Polly's exit to occur mid-serial, and so the renewal of Michael Craze's contract on January 27th was for the same length of time.

The director assigned to The Macra Terror was John Davies; this would be his only work on Doctor Who. Location filming took place on February 15th at an Associated Portland Cement Manufacturers Ltd quarry at Dunstable in Bedfordshire, for material in the wasteland where the TARDIS materialised. On February 17th, scenes involving the Controller were filmed at the BBC Television Film Studios in Ealing, London. Davies also recorded a shot of a Macra claw which would appear on the TARDIS scanner at the end of The Moonbase, the serial preceding The Macra Terror.

The final episode of The Moonbase had seen Doctor Who return to its original production home of Lime Grove Studio D in Shepherd's Bush, London. All four parts of The Macra Terror were made there on consecutive Saturdays, starting with Episode One on March 4th. Polly sported a shorter hairstyle in this episode as a result of her makeover in the colony's Refreshing Department. Although some reports have suggested that this reflected Wills' decision to restyle her own hair (resulting in her wearing extensions during the episode's early scenes), Wills herself has indicated that she donned a pixie-cut wig to hide her (uncut) long hair.

Episode One began with the new Doctor Who title sequence, which had been recorded back on December 9th. Bernard Lodge drew on unused ideas for the original 1963 version, in which he had experimented with incorporating a person's features into the electronically-generated graphics. Then-producer Verity Lambert had feared that the technique was too scary and had forbidden its use, but Innes Lloyd now liked the concept, and agreed that a photocaption of Patrick Troughton's face should be used for the new credits. This would become a hallmark of many future Doctor Who opening sequences.

Unfeasibly large, the Macra had to be mounted on a van in order to be moved

March 4th also saw the unveiling of the full-sized Macra. The unfeasibly large prop needed to be mounted on a van in order to be moved, and was therefore very awkward to manipulate in the studio. Lloyd was unhappy with the work of Shawcraft Models on The Macra Terror, and contacted the BBC's Visual Effects Department for guidance as to whether the monster should reasonably have cost the £500 paid to the propmakers. Because only one Macra was constructed for the serial, the closing moments of Episode Three -- in which Jamie was menaced by two of the monsters -- had to be recorded out of sequence on March 18th. First Davies taped all of the scenes involving the Macra which moved from right to left, followed by those in which the “other” Macra moved from left to right.

The recording of Episode Four on March 25th completed production on The Macra Terror. Unusually, actress Sandra Bryant, who had played Chicki in Episode One, asked that the role be recast for the concluding installment. Lloyd agreed to her request on March 10th, and Karol Keyes was hired to replace Bryant. The broadcast of this episode on April 1st was accompanied by a change to the BBC's Saturday evening schedules. The Monkees, which had been following Doctor Who for the past three months, was now moved later in the evening. Doctor Who would instead lead into a new run of the sitcom The Dick Van Dyke Show.

• Doctor Who Magazine #308, 19th September 2001, “Archive: The Macra Terror” by Andrew Pixley, Panini Publishing Ltd.
• Doctor Who Magazine #536, April 2019, “Feeling The Pinch” by Paul Kirkley, Panini UK Ltd.
• Doctor Who Magazine Special Edition #4, 4th June 2003, “Good Vibrations” by Andrew Pixley, Panini Publishing Ltd.
• Doctor Who: The Complete History #10, 2017, “Story 34: The Macra Terror”, edited by Mark Wright, Hachette Partworks Ltd.
• Doctor Who: The Handbook: The Second Doctor by David J Howe, Mark Stammers and Stephen James Walker (1997), Virgin Publishing.
• Doctor Who: The Sixties by David J Howe, Mark Stammers and Stephen James Walker (1992), Virgin Publishing.