A message transmitted down through history draws the Doctor and Amy to England in AD 102. There they find River Song waiting for them, with a warning that a legendary prison called the Pandorica -- hidden beneath Stonehenge -- is about to open. Too late, the Doctor realises that the Pandorica is actually a trap set for him by an alliance of his enemies. They hold him responsible for the cracks in time, and want to prevent universal destruction. Meanwhile, a mysterious force has seized control of the TARDIS, setting in motion the very explosion which the Pandorica was intended to prevent. Will silence fall across all time and space?

Ever since Doctor Who returned to television in 2005, each season had featured an ongoing plot which culminated in the two-part final story. The preference of former executive producer Russell T Davies had been to seed ideas into earlier episodes which would foreshadow the climactic adventure. For instance, the phrase “Bad Wolf” appeared throughout Season Twenty-Seven, and was ultimately revealed to have been planted by companion Rose Tyler after she absorbed the power of the time vortex. Davies' successor, Steven Moffat, aimed to uphold this tradition for Season Thirty-One. However, he also wanted to make the season finale a direct sequel to as many of the year's adventures as he could, by incorporating characters who had appeared in earlier stories.

The three main components of the overall story arc were established in the season premiere, The Eleventh Hour. It focussed on a crack in time on the bedroom wall of companion Amy Pond, while the villainous Prisoner Zero warned the Doctor that the mysterious Pandorica would open and proclaimed that “Silence will fall”. The crack appeared again on the side of Starship UK in The Beast Below, on a wall in the Cabinet War Rooms in Victory Of The Daleks, aboard the crashed Byzantium in Flesh And Stone, within a cavern in the Silurian city of Cold Blood, and behind Craig Owens' refrigerator in The Lodger. In Flesh And Stone, River Song mentioned that the Doctor would next encounter her at the opening of the Pandorica. Finally, the Saturnynes of The Vampires Of Venice claimed to have fled the Silence through a crack in time.

Every Season 31 adventure would have an explicit link to the finale except for Amy's Choice

To revisit several of the season's earlier adventures, Moffat invented the device of the Doctor being sent a message through time. It would connect characters from The Beast Below, Victory Of The Daleks and Vincent And The Doctor, and culminate in the reappearance of River Song. Relevant sequences could then be filmed alongside the appropriate stories throughout the production schedule. As a result, every Season Thirty-One adventure would have an explicit link to the finale except for Amy's Choice.

The level of planning required to pull all of this off meant that Moffat had to start hammering out the details of the climactic serial at a very early stage. Fortunately, doing so helped facilitate another wrinkle in the structure of the season. Moffat often liked to tell stories out of chronological order, and he was keen to slip a scene into an earlier episode which viewers would only later realise took place during the narrative of the finale. He quickly identified the year's fifth installment, Flesh And Stone, as the appropriate venue for this twist. As such, it would feature a scene in which the time-displaced Doctor of the concluding serial implored Amy to remember the words he spoke to her when she was seven years old -- words the viewer would not witness until the year's last episode. The notion of a character travelling backwards along his own timeline was a concept Moffat remembered encountering in 1972's The Making Of Doctor Who, the milestone behind-the-scenes chronicle written by Malcolm Hulke and Terrance Dicks.

As a result, the first filming for the finale was the cross-over with Flesh And Stone. It was directed by Adam Smith at Puzzlewood near Coleford, Gloucestershire on July 29th, 2009 during Season Thirty-One's first production block. Then, during Block Two, Andrew Gunn filmed several scenes which would comprise part of the sequence depicting the message through time. On August 26th, Prime Minister Winston Churchill and Edwin Bracewell from Victory Of The Daleks examined a mysterious painting in the Cabinet War Rooms, really the bunker of the Joint Resilience Unit in Swansea. The preceding shot of Bracewell hurrying along a corridor was taped on August 31st at Brackla Bunkers in Bridgend. Then, on September 22nd at the Orangery in Margam, Gunn shot elements of the Buckingham Palace meeting between River Song and Liz Ten, the monarch from The Beast Below.

Steven Moffat was effectively stripped of nearly two months' writing time

While all of this preliminary work was going on, the Doctor Who production team learned that the original plan for the season's shooting schedule was not feasible. It was anticipated that the two-part finale would be made as Block Seven, the last recording block of the year. However, early in the autumn, it became clear that this would give effects house The Mill insufficient time to complete their contributions to what would no doubt be an ambitious pair of episodes. Instead, the two installments would have to be made as Block Six. Effectively stripped of nearly two months' writing time, Moffat spent the remainder of 2009 busily working on his scripts. The episodes became known as The Pandorica Opens and The Big Bang. While the latter ostensibly referred to the universe being rebooted, Moffat privately meant it to be a double entendre which alluded to Amy and Rory conceiving a child after departing in the TARDIS at the story's end. This would be a key plot point for Season Thirty-Two.

One of Moffat's intentions for the finale was to indulge in some wish fulfilment by confronting the Doctor with an army of his past foes. The Pandorica Opens would ultimately feature either appearances by, or references to, the Daleks (most recently seen in Victory Of The Daleks), the Cybermen (The Next Doctor), the Sontarans (The Sontaran Stratagem / The Poison Sky), the Autons and the Nestene Consciousness (Rose), the Silurians (The Hungry Earth / Cold Blood), the Atraxi (The Eleventh Hour), the Judoon (Smith And Jones), the Roboforms (The Runaway Bride), the Hoix (Love & Monsters), the Sycorax (The Christmas Invasion), the Slitheen (Boom Town), the Terileptils (The Visitation), the Zygons (Terror Of The Zygons), the Draconians (Frontier In Space), and the Drahvins (Galaxy 4). Three races hailed from Doctor Who's spin-off series: the Weevils and the Blowfish aliens had both appeared in Torchwood, while the Uvodni had been seen in The Sarah Jane Adventures. Not previously mentioned on television were the Chelonians; instead, they were a memorable creation of Gareth Roberts' for his 1993 novel The Highest Science, part of the Doctor Who: The New Adventures range from Virgin Books.

Moffat felt that such an epic showdown demanded an equally epic setting, which led him to situate the key events of The Pandorica Opens around -- and below -- Stonehenge. A massive stone circle on the Salisbury Plain near Amesbury in Wiltshire, Stonehenge had been a source of national and international fascination for hundreds of years. Built in stages during the third and second millennia BC and aligned with the sun on the summer and winter solstices, its original purpose remained a subject of great speculation and debate, providing Moffat with a perfect opportunity to conceive a Doctor Who explanation for its construction. Access to the site was now heavily restricted to limit erosion and damage to the ancient monument, and so consideration was given to filming at a different stone circle. Fortunately, the production team was ultimately able to secure one night's filming at Stonehenge itself.

The story's cataclysmic stakes warranted the Doctor breaking the rules by which he normally lived

Another way that Moffat wanted The Pandorica Opens / The Big Bang to exploit chronology was by having the Doctor use time travel to manipulate the course of events more explicitly than Doctor Who had previously depicted. To this end, he incorporated a complex sequence in which the Doctor hopped back and forth through time in order to save Amy and then gain access to the Pandorica. Moffat acknowledged that this kind of paradoxical business could undermine the drama of Doctor Who, but he felt that the story's cataclysmic stakes warranted the Doctor breaking the rules by which he normally lived.

Moffat completed his first draft of The Pandorica Opens / The Big Bang on December 1st. A late addition to the finale was the stone Dalek, which Moffat devised after realising that The Big Bang lacked an imminent, tangible threat. To help viewers navigate the complexities of the Doctor's time-bending, he included the elements of the fez and the mop, which would serve as visual clues. Dorium Maldovar was inspired by Signor Ferrari, the portly black marketeer played by Sydney Greenstreet in the 1942 movie classic Casablanca. River Song's message to the Doctor on the cliff at Planet One was originally “Doctor, I need you”, in reference to the way Diana Rigg's super-spy Emma Peel was regularly summoned by her partner, John Steed, in Sixties icon The Avengers.

Meanwhile, occasional filming for the finale was still taking place in advance of the main shoot. On December 3rd, during Block Five, an establishing shot of Vincent van Gogh's Yellow House -- as seen in Vincent And The Doctor -- was captured by director Jonny Campbell in Vrsine, Croatia. The finale's reins were then turned over to the serial's principal director, Toby Haynes, who was a lifelong Doctor Who fan. His first day of recording came on December 15th, while Block Five was still in production. Campbell's team was at Sutton Farm in Llandow to record more material at the Yellow House, and Haynes briefly took over to record the opening segment in which van Gogh's ominous painting was discovered.

Block Six officially got under way on January 14th and 15th, 2010 with recording on the standing TARDIS set at Doctor Who's regular studio home in Upper Boat. The following week -- from the 18th to the 23rd -- was spent at Brangwyn Hall in Swansea, which served as the National Museum where the Pandorica was on display. Caitlin Blackwood reprised the role of the young Amelia she had originated in The Eleventh Hour; this time, however, she actually got to share screen time with her cousin, Karen Gillan. The two stone Daleks were modified versions of the blue and orange Paradigm Dalek casings created for Victory Of The Daleks. During the last day at Brangwyn Hall, shots of the Doctor piloting the Pandorica were also taped.

Toby Haynes suggested to Steven Moffat that he might considering bringing Dorium Maldovar back in a future adventure

Sunday the 24th was a rest day. On the 25th, additional material in the National Museum -- particularly in the foyer -- was filmed at the eminently suitable venue of the National Museum of Wales in Cardiff. The same day, more Cardiff recording included the Stormcage sequence at the Millennium Stadium, as well as River's meeting in the Maldovarium, which occurred at the Crystal nightclub. Playing Dorium was Simon Fisher-Becker, a veteran character actor who was also a longtime Doctor Who fan. Haynes was impressed with his performance, and suggested to Moffat that he might consider bringing Dorium back in a future adventure. On January 26th, the Miskin Manor Hotel in Miskin was the site of Amy and Rory's wedding reception. Work there concluded on the 27th, at which point the cast and crew relocated to the Vicarage in Rhymney. It again served as Amy's house in Leadworth, as in The Eleventh Hour. Haynes' team remained in Rhymney until January 29th, when the Vicarage also hosted the scene in Rory's bathroom.

Following another full weekend's break, Margam Country Park in Margam -- the location of the Orangery -- was the week's main location. Work there began on February 1st, when its grounds were the site of the Roman encampment. The same day, Haynes recorded close-ups of the Doctor, Amy and River traversing the English countryside, chiefly using a mechanical riding simulator as opposed to real horses. The work at Margam was paused on the 2nd, because this was the day that Doctor Who had been provided access to Stonehenge. With the site open to the public for much of the day, cast and crew had to take full advantage of the time in-between, with a particular emphasis on the single hour of daylight they would enjoy the following morning. It was back to Margam on February 3rd, where a replica of Stonehenge had now been constructed. Work on “Foamhenge” continued through to the 5th and allowed for shots forbidden at the real Stonehenge, such as the Doctor standing atop one of the megaliths -- something Matt Smith had been disappointed to learn was not permitted at Wiltshire. Part of the last day was spent back at the Orangery, with Alex Kingston recording River Song's half of her encounter with Liz Ten in Buckingham Palace. The work week ended at Upper Boat on February 6th, when Haynes filmed scenes in the Roman tent, alongside further material in the TARDIS and various inserts.

A day off on Sunday the 7th was followed by a week at Upper Boat, spanning February 8th to 12th. The main focus was the massive “Underhenge”, which was the largest set yet constructed for Doctor Who and had been designed to evoke the feel of the 1981 blockbuster Raiders Of The Lost Ark. Other recording on the 8th saw the injured Doctor enter the Pandorica and Amy revealed as its prisoner at the start of The Big Bang. On the 9th, the cast was joined by actor Tim Baggaley who, as an amputee, was able to bring the one-armed Cyberman to life without the need for complicated effects work. Moffat was delighted with this element of the serial, and particularly with the effectiveness of the Cyber-head, a concept which he now planned to revisit in the future. A second unit was also active on the 10th, with producer Peter Bennett directing River's discovery that she was trapped in the TARDIS at the end of The Pandorica Opens.

The production was again stood down for the weekend, after which cameras continued to roll at Upper Boat from February 15th to 17th. Haynes completed the scenes in the Underhenge during the first two days. Given the modifications which had been made to their blue and orange brethren, only the white, red and yellow Paradigm Daleks were present for the climax of The Pandorica Opens. The last day was principally given over to effects and insert shots, but Haynes also recorded the Doctor and Amy arriving on Planet One. Meanwhile, Bennett's second unit travelled to Gelligaer Common in Gelligaer to tape long shots of the Doctor, Amy and River on horseback, using stand-ins for the main cast.

Haynes taped additional inserts -- largely involving the headless Cyberman -- at Upper Boat on March 3rd. This left only the scene of the Doctor watching as Amy placed the note which would direct him to Craig Owens, as implied by the events of The Lodger. It was filmed in two parts at different locations in Cardiff: Westville Road on March 4th and Taff Terrace on March 18th.

It was thought that Pyroviles and Vespiforms might be present at the end of The Pandorica Opens

Both episodes were given extended timeslots: fifty minutes for The Pandorica Opens and fifty-five minutes for The Big Bang. As a result, few substantial edits had to be made. Dropped from the first installment was Liz Ten's explanation that most of the residents of Starship UK were now back on Earth, but that she had remained behind to care for the ageing Star Whale. Budgetary considerations also forced the exclusion of purely computer-animated monsters from the closing moments of The Pandorica Opens. Originally, it was thought that the Pyroviles of The Fires Of Pompeii and the Vespiforms of The Unicorn And The Wasp might be present alongside the various other alien races.

As had been the case throughout Season Thirty-One, Doctor Who's start time varied for both installments of the concluding adventure. The Pandorica Opens was broadcast at 6.40pm on June 19th, and was preceded by the second of two Total Wipeout specials. A week later, The Big Bang appropriately drew the season to a close at 6.05pm on the date of Amy and Rory's wedding: June 26th. On this occasion, its lead-in was the celebrity competition Hole In The Wall. The National Lottery: In It To Win It, which had been airing after Doctor Who for the latter part of the season, was pushed later into the evening by a Total Wipeout repeat. With the conclusion of Season Thirty-One, the Doctor Who timeslot would next be occupied by 101 Ways To Leave A Gameshow.

Despite Season Thirty-One witnessing a complete changeover of cast and production team, Doctor Who remained a massive success, regularly placing within the week's Top Twenty programmes. Even more remarkably, it was still tapping into new audiences, having become one of the most popular downloads via the BBC's iPlayer service, while reaching unprecedented heights of popularity in North America. 2010 may have been a year of transition for Doctor Who, but its latest regeneration had simply ensured that the show's future remained bright...

• Doctor Who Magazine Special Edition #27, 16th March 2011, “The Pandorica Opens / The Big Bang” by Andrew Pixley, Panini Publishing Ltd.
• Doctor Who: The Complete History #66, 2017, “Story 212: The Pandorica Opens / The Big Bang”, edited by John Ainsworth, Hachette Partworks Ltd.