The Doctor and Clara travel to Caliburn House in 1974. The owner of the estate, Alec Palmer, is investigating the Witch of the Well, a ghost which has stalked the halls of Caliburn House for centuries -- and whose legend even predates the mansion's construction. To assist him, he has recruited an empathic telepath named Emma Grayling, who can sense the ghost's immense loneliness. The Doctor discovers that the Witch of the Well is a mystery which transcends time and space -- and that the ghost is not the only thing haunting Caliburn House.

A lifelong Doctor Who fan, Neil Cross had hoped to write for the programme when Russell T Davies was its executive producer, only for these plans to fall foul of scheduling difficulties. In 2011, however, Cross' friend, Caroline Skinner, joined Davies' successor, Steven Moffat, as Doctor Who's executive producer. She encouraged Moffat to approach Cross, and this time it became clear that the writer would be able to provide a script for the second stage of Doctor Who's thirty-third season. This block of eight episodes would be made immediately after the five installments destined to air in the autumn of 2012, but would be held over until the spring of 2013. They would see the Doctor travelling with a new companion, who at this stage was envisaged as a Victorian-era governess named Beryl; she would be introduced in the 2012 Christmas special, The Snowmen.

Cross had grown up a fan of Doctor Who as made in the Seventies and early Eighties, when the Doctor was played by Jon Pertwee, Tom Baker and Peter Davison. He was eager to write a spooky story of the sort which had been predominant during Baker's early years in the role. Cross also fondly remembered the work of Nigel Kneale, creator of the Quatermass serials, and he particularly looked to Kneale's 1972 ghost story, The Stone Tape. He decided to develop a haunted house adventure in which he hoped Kneale's Bernard Quatermass character might take a central role; however, when it became clear that rights issues would preclude this crossover, Cross created Alec Palmer instead.

Neil Cross intended the entire narrative to be set within the walls of Caliburn House

Palmer would be depicted as the owner of Caliburn House, which would serve as the story's principal setting. It was named in reference to King Arthur's sword in the writings of Geoffrey of Monmouth, which later evolved into the more familiar Excalibur. Indeed, Cross originally intended the entire narrative to be set within its walls, with the extra-dimensional space -- which he dubbed the Hex -- represented by a daylight version of Caliburn House's interior. However, Moffat felt that the narrative deserved a larger scale, and he suggested that the Hex should instead take the form of an eerie wood.

By late January 2012, the production team had reversed course on the new companion, and decided that the character -- now named Clara -- should originate from contemporary Britain. Nonetheless, Moffat was mindful that the Doctor would need to have a compelling reason to take Clara aboard the TARDIS, given the tragic circumstances surrounding the departures of recent companions Donna, Amy and Rory. To this end, he began to develop a complex puzzle which would surround Clara, including the appearance of lookalike characters in other times and places. The role of Beryl in The Snowmen would now be filled by one of these echoes, while another was inserted into the script for the season premiere, Asylum Of The Daleks. Clara would still debut in The Snowmen, but only in a coda at the end of the episode; her first full story would be The Bells Of St John, the initial adventure of the 2013 run.

Cross was briefed on these changes, and the modern-day Clara was incorporated into his first draft script. Entitled “Phantoms Of The Hex”, it was completed on April 15th. At this stage, the Hex was the prison of the Lost Lord, an ancient Time Lord also called the Revenant of Anathenon who had become trapped there so long ago that he was now just a bogeyman of Gallifreyan legend. The Lost Lord sought to tempt the Doctor into the Hex and feed on him, enabling him to return to the normal universe where he would begin absorbing all of time.

By May, the Lost Lord element of “Phantoms Of The Hex” was discarded along with the associated continuity baggage, to be replaced by the Crooked Man. However, Moffat became concerned that a straightforward monster was unsuitably shallow. He worked with Cross to develop the idea of the two Crooked Men and the love which bound them, reinforcing themes already present in the storyline. Around this time, the story became known as “The Hider In The House”.

Hide was the first of Clara's adventures to go before the cameras

At this point, Cross' adventure was intended to air fifth out of the eight episodes comprising the second segment of Season Thirty-Three; it would later be pushed back to sixth before finally being broadcast fourth. However, it would be the first of Clara's adventures to go before the cameras. The sole episode to comprise the year's fourth recording block, its director was Jamie Payne. Jenna-Louise Coleman had already won the role of Clara, since she had been needed to play Oswin -- the first of Clara's echoes -- for Asylum Of The Daleks at the end of April. Coleman was uneasy about diving straight into the middle of Clara's adventures before filming her introduction -- a circumstance created in part by the lateness of the script for The Snowmen -- but Moffat and Payne both worked to assuage her concerns.

Following the conclusion of principal photography on The Power Of Three, the last Amy-Rory story to go before the cameras, production on Doctor Who stood down for a week. As such, it wasn't until May 22nd and 23rd that recording began on “The Hider In The House”, at Plas Llanmihangel near Cowbridge in the Vale of Glamorgan. Now a bed-and-breakfast establishment, the manor house dated from at least 1166; it provided the dining room of Caliburn House. The Doctor's new purple coat made its debut, satisfying Smith's long-held desire for an outfit in this colour, and advancing an overarching scheme for his incarnation's attire to evolve over time. On May 24th and 25th, Tyntesfield House in Wraxall, Bristol offered spaces suitable for the great hall, the stairs, the kitchen and various corridors. On May 26th, during a weekend off, Matt Smith became the first Doctor Who star to participate in the Olympic torch relay, as part of the build-up to the 2012 Summer Games in London.

The last day at Tyntesfield House was May 28th. On the 29th, some of the material in the Hex pocket universe was filmed in Gethin Woodland Park near Abercanaid. Payne had argued for the Crooked Man to be realised chiefly as a practical rig, in order to achieve a visual aesthetic similar to the classic 1982 horror film Poltergeist. More material in the forest was completed on May 30th and 31st at Margam Country Park in Margam; this venue also provided the exterior and grounds of Caliburn House, as well as the primeval jungle. On June 1st, Payne's team shifted to Hensol Castle in Hensol for sequences in the music room and the dark room.

After another full weekend of rest, cast and crew reassembled at Hensol Castle on June 4th, before returning to Gethin Woodland Park on the 5th. “The Hider In The House” was now largely complete, although effects shots of the Doctor tumbling through the wormhole were filmed on June 19th, outside Doctor Who's new regular facilities at Roath Lock Studios in Cardiff. Still to come were the TARDIS scenes, which could not be taped alongside the rest of the episode because the new console room set -- which would debut on-screen in The Snowmen -- was not yet finished. This work was finally carried out at Roath Lock on September 22nd. Additional inserts were then recorded in the studio on October 18th and November 27th.

In post-production, dubbing replaced all references to the Hex with less oblique terminology for the pocket universe. Then, in early 2013, the episode's title was truncated to Hide. Its April 20th broadcast coincided with a shake-up of BBC One's Saturday schedule. The Voice UK, which had been airing after Doctor Who, now moved later in the evening to avoid overlapping with ITV's highly-rated Britain's Got Talent. Accommodation also had to be made for the transmission of qualifying highlights from the Bahrain Grand Prix. As a result, Hide aired at 6.45pm, three quarters of an hour later than the season's third episode, Cold War. It was preceded by the Formula One competition, as well as a news update, while Doctor Who now led into the sixth season of the National Lottery quiz show Who Dares Wins.

• Doctor Who Magazine Special Edition #37, Autumn 2014, “Hide” by Andrew Pixley, Panini UK Ltd.
• Doctor Who: The Complete History #73, 2016, “Story 235: Hide”, edited by John Ainsworth, Hachette Partworks Ltd.