All over the world, people are found dead, slumped next to their computers. What no one realises is that the victims' minds are being harvested, uploaded through an insidious new wi-fi network run by Miss Kizlet on behalf of an enigmatic client. Using robotic servers called Spoonheads, Miss Kizlet's reach extends virtually everywhere -- and to almost everyone. But her latest victim, a young nanny named Clara Oswald, has already made contact with the Doctor under mysterious circumstances. Having realised that Clara is the same woman he has already seen die twice, the Doctor is determined not to lose her for a third time.

Although it was known since early 2011 that the latter part of Doctor Who's thirty-third season would introduce a new companion for the Doctor, plans for the character evolved considerably over the span of a few months between late 2011 and the start of 2012. Instead of a Victorian governess called Beryl who cared for Charlotte and Godfrey, the Doctor would now be accompanied by a contemporary woman named Clara who worked as a nanny to young Angie and Artie Maitland, but yearned to travel. As a result, although the modern-day Clara would make a brief appearance at the end of the 2012 Christmas special, The Snowmen, the task of establishing her now effectively shifted to the first episode of Doctor Who's eight-part Spring 2013 run. Furthermore, executive producer Steven Moffat had crafted a mystery surrounding Clara, who would appear to be identical to two ill-fated characters whom the Doctor had recently encountered: Oswin in the Season Thirty-Three premiere, Asylum Of The Daleks, and a nineteenth-century Clara in The Snowmen. This story arc would now have to ratchet up a gear, setting the stage for its resolution in the season finale.

Moffat began working on ideas for Clara's debut adventure around April 2012. In the past, he had gotten considerable mileage out of turning the familiar and commonplace into sources of menace or mystery -- such as statues in 2007's Blink or cracks on a bedroom wall in 2010's The Eleventh Hour. At the time, wi-fi networks were still relatively new technology but were fast becoming omnipresent, and Moffat had been struck by the way they would pass in and out of the range of his laptop as he rode the train between London and Cardiff. This led to the notion of a rogue wi-fi network -- an idea which Moffat could marry to producer Marcus Wilson's suggestion of an urban thriller along the lines of recent James Bond movies like 2006's Casino Royale, or the film adaptations of Robert Ludlum's Bourne spy novels such as 2002's The Bourne Identity.

In several drafts, the Great Intelligence confronted the Doctor via Clara's laptop

Dubbing his script The Bells Of Saint John, Moffat completed a first draft around the end of August. The placement of Cloud Incorporated's headquarters within the Shard skyscraper near London Bridge was intended to give the story a highly contemporary feel: the edifice would not open to the public until February 1st, 2013. Originally, there was no explicit reference to the identity of Miss Kizlet's client. In subsequent drafts, however, the face of Dr Simeon -- whom the Great Intelligence had possessed in The Snowmen -- confronted the Doctor via Clara's laptop. Only latterly was the Great Intelligence's involvement made known to the audience, but not the Doctor.

For a time, it was thought that the troops who arrested Miss Kizlet might be accompanied by Kate Stewart, the new head of the Unified Intelligence Taskforce, who had been introduced in The Power Of Three earlier in Season Thirty-Three. The book by Amelia Williams -- that is, former companion Amy Pond -- was initially called One Deadly Summer before becoming Summer Falls; its text would later be published online and then form part of a print anthology, ghost-written by James Goss. Until a very late stage, the Doctor found a sheet of passport photographs in Clara's travel book rather than a leaf. This was changed to tie into The Rings Of Akhaten, the next story in both the recording and transmission schedules.

The Bells Of Saint John went into production on its own as Block Eight, and would be the only Doctor Who story directed by Colm McCarthy. To afford Wilson time to begin planning for Doctor Who's upcoming golden anniversary story, Denise Paul produced The Bells Of Saint John. She had worked in the same capacity on Closing Time during Season Thirty-Two; Wilson would instead be credited as the series producer. Joining the Doctor Who cast for several episodes were the two young actors playing Clara's charges: Eve De Leon Allen as Angie and Kassius Carey Johnson as Artie. Both had previously appeared in shows for the preschool-oriented CBeebies channel. Because the middle part of the Spring 2013 run had gone before the cameras prior to The Bells Of Saint John as Moffat worked to catch up on his scripts, Jenna-Louise Coleman had already portrayed the twenty-first-century Clara in four full adventures, in addition to her cameo at the end of The Snowmen.

The first scene filmed for The Bells Of Saint John was Nabile's video. It was taped at Doctor Who's usual production facilities, Roath Lock Studios in Cardiff, on September 24th while work on Block Seven -- Journey To The Centre Of The TARDIS -- was wrapping up. At this stage, Nabile was played by Fady Elsayed, who would later star as Ram Singh in the 2016 spin-off series Class. There was then a two-week hiatus, while Moffat travelled to the United States to participate in various promotional events organised by BBC America. In the interim, production company Midnight Oil, which was developing a documentary entitled Doctor Who: The Companions, captured all of the footage of the Spoonheads' victims which would be visible on nearly one hundred screens at Cloud Incorporated.

Recording for The Bells Of Saint John resumed at a house on Beatty Avenue in Cardiff, which served as the Maitland residence from October 8th to 10th. McCarthy primarily concentrated on aeroplane sequences on the 11th; the craft was provided by eCubed Solutions at MOD St Athan. The same day, two sites represented the year 1207: the monastery exterior was Southerndown Beach, at Southerndown in Ogmore Vale, while the burial chamber containing the TARDIS was a set erected at Roath Lock. Then it was back to Beatty Avenue on October 12th, before a day off on Saturday the 13th.

Cast and crew headed for London on October 15th and 16th

The second week of filming began on October 14th with a day on the standing TARDIS set at Roath Lock, after which cast and crew headed for London. The main focus on the 15th was the rooftop cafe at Grange St Paul's Hotel in the City of London. Meanwhile, motorcycle shots of the Doctor and Clara -- as played by their stunt doubles, Andy Godbold and Dani Biernat -- were captured at a number of landmarks, such as Waterloo Bridge in Waterloo, plus Westminster locations including Horse Guards Road, Westminster Bridge, and Admiralty Arch at The Mall. Plate shots of the Shard in Southwark were also recorded. On the 16th, the TARDIS materialised on the Queen's Walk in Westminster, before it was Smith and Coleman's turn to ride the motorcycle at Waterloo Bridge and Westminster Bridge, and finally arrive outside the Shard. It was back to Wales and the thirteenth century on October 17th, with the burial mound situated at Fforest Fawr in Taff's Well, and Caerphilly Castle in Caerphilly providing the monastery interior and courtyard. The 18th was a studio day, with material in the Cloud Incorporated offices and footage of the newsreader on the agenda. Work on the 19th began at the Senedd in Cardiff for sequences inside the cafe, before McCarthy's team returned to the TARDIS set at Roath Lock.

After the weekend, the bulk of the remaining scenes took place within the premises of Cloud Incorporated; they were completed at Roath Lock on October 22nd and 23rd. The 24th then saw various pick-up shots recorded in the studio and on the streets of Cardiff. On November 9th, a new scene of the Doctor changing out of his monastic garb was taped on the TARDIS set at Roath Lock, while the effects shots of the Doctor driving up the side of the Shard were recorded against a green screen. Richard E Grant's contribution as Dr Simeon was then filmed in the studio on November 21st, during work on the season finale, The Name Of The Doctor.

On November 26th, a prequel for The Bells Of Saint John was recorded by director John Hayes at Roath Park in Cardiff. Written by Moffat, it depicted the Doctor discussing his search for Clara with a little girl... who turned out to be a young Clara. The child was played by Sophie Downham, who would also appear in The Name Of The Doctor. Clara's mum, Ellie, was portrayed by Nicola Sian; she had been cast in the same role for The Rings Of Akhaten.

Colm McCarthy went abroad to record additional footage for the pre-credits sequence

Meanwhile, the global appeal of Doctor Who was on the rise, and the production team was keen to embrace an international scope. To this end, it was decided to send McCarthy abroad to record additional footage for the pre-credits sequence which would open The Bells Of Saint John. On December 2nd, he captured sequences at the London St Pancras International station in St Pancras, London, aboard a Eurostar train travelling between London and Paris, and at the Eiffel Tower in Paris. Farther abroad, McCarthy taped material in the United States -- near the Golden Gate Bridge in San Francisco, California -- on December 6th. Finally, he moved on to Tokyo, Japan, where his cameras rolled in the Shibuya district on the 8th and near the Sensō-ji temple on the 9th. McCarthy's expedition meant that Nabile's video would have to be correspondingly remounted. This work was undertaken on February 18th, 2013 at BBC Television Centre in White City, London; Manpreet Bachu replaced Fady Elsayed in the role of Nabile.

One significant edit came towards the end of The Bells Of Saint John. It saw the Doctor contemplating images of Oswin and the Victorian-era Clara when the TARDIS phone rang again, and a whispered female voice on the line implored him to trust Clara and take her with him. This sequence had replaced an earlier version which took place after Clara was attacked by the Spoonhead, with the voice telling the Doctor, “Run you clever boy. And save her,” echoing similar dialogue from Asylum Of The Daleks and The Snowmen.

The prequel to The Bells Of Saint John was released online on March 23rd, and ran to a total of one hundred and fifty-four seconds. Season Thirty-Three then resumed one week later, on March 30th; ninety-five days had elapsed since The Snowmen, and no fewer than one hundred and eighty-two days since the Fall 2012 finale, The Angels Take Manhattan, exactly half a year earlier. The Bells Of Saint John aired at 6.15pm, a timeslot which had generally been occupied by sporting events and the quiz show Pointless Celebrities in recent weeks. Pointless Celebrities was now scheduled earlier in the afternoon to lead into Doctor Who, with a news update falling in-between. The season premiere of The Voice UK was broadcast immediately following The Bells Of Saint John.

• Doctor Who Magazine Special Edition #37, Autumn 2014, “The Bells Of Saint John” by Andrew Pixley, Panini UK Ltd.
• Doctor Who: The Complete History #72, 2017, “Story 232: The Bells Of Saint John”, edited by John Ainsworth, Hachette Partworks Ltd.