An enigmatic message sends the Doctor and Donna to a planet-sized library. They arrive to find the world deserted, except for an archaeological expedition led by Professor River Song, who claims to know the Doctor of old. Joining forces, the Doctor and River investigate the mystery of why the library was sealed off a century earlier. But the shadows are alive with a flesh-consuming intelligence... and somewhere, a little girl believes that all of these events are playing out in her mind.

After writing The Empty Child / The Doctor Dances for Doctor Who's 2005 season, Steven Moffat was asked to come up with ideas for the subsequent run of episodes. His initial concept was a story about a library in space which contained portals to other libraries throughout history, and which was menaced by monsters which appeared in the form of angelic stone statues. Executive producer Russell T Davies was enthusiastic about Moffat's proposal, but was eager for the writer to tackle an adventure with historical elements. Retaining only the windows through time, Moffat conceived The Girl In The Fireplace.

The next year, Moffat again wanted to make use of his library notion for the 2007 season. However, he was aware that this idea would need two episodes to be properly developed, and although Davies hoped he might be able to supply these scripts for early in the run, Moffat's other commitments precluded this. Instead, he opted to tackle the late-season “Doctor-lite” episode, and resurrected the angelic statues for what would become Blink.

Finally, Moffat was determined to write the library adventure for 2008, and he began working on them around July 2007. At about the same time, he was approached by Davies with a staggering offer. After six years at the helm of Doctor Who, Davies planned to leave the show following a series of specials which would air throughout 2009. He asked Moffat to succeed him as executive producer and head writer, beginning with the next full season which would air in the spring of 2010. Although this was Moffat's self-confessed dream job, he had to weigh the offer carefully against the battery of original projects that he wanted to work on, in addition to the personal upheaval involved in moving to Doctor Who's production base in Cardiff for much of the year. Nonetheless, on October 26th, Moffat formally accepted the position.

Davies' job offer had a profound effect on the development of Moffat's scripts, which became known as Silence In The Library and “The Doctor Runs” (the latter an echo of Moffat's 2005 script, The Doctor Dances). Eager to assure viewers that Doctor Who's future was an exciting time that they should look forward to witnessing, he decided to introduce a character who had already met a later incarnation of the Doctor. This became Professor River Song, whose exact relationship with the Time Lord he kept intentionally enigmatic.

Other alterations to the story included the child in the computer being changed from a boy to a girl, as it was felt that a young female character would be seen as more vulnerable. A twist revelation in which Donna's artificial-reality husband, Lee, turned out to be an overweight woman in the real world was also excised, for fear of being too confusing. Donna's illusory children were initially called Alan and Tracy, but they were renamed Joshua and Ella, after Moffat's son and one of his son's friends.

Moffat's scripts -- now known as Silence In The Library and “Forest Of The Night” -- were originally scheduled as the ninth and tenth episodes of the 2008 season. During the autumn, however, it was realised that both this tale and the story intended to follow it, Turn Left, featured elements of Donna living in some sort of imaginary world. Consequently, around the end of October, Moffat's serial was brought forward by one episode, with Midnight now separating the two narratives. Silence In The Library and “Forest Of The Night” were assigned to the season's eighth production block. The director would be Euros Lyn, whose most recent Doctor Who work had been on the 2006 Christmas special, The Runaway Bride.

Cast in the pivotal role of River Song was Alex Kingston. As a girl, Kingston had been encouraged to act by one of her teachers; an early theatre role saw her performing opposite Sean Pertwee, the son of Third Doctor Jon Pertwee. Kingston joined the Royal Shakespeare Company and earned a number of credits in British television, including episodes of Grange Hill, The Bill and The Knock. She also appeared in movies such as The Cook, The Thief, His Wife, And Her Lover. In 1997, Kingston gained international acclaim when she was offered a starring role in the long-running American medical drama ER. Kingston took the part of River Song under the assumption that the character would appear only in Silence In The Library and “Forest Of The Night”. However, she was delighted to learn that Moffat had longer-term plans for the character.

Filming began on January 15th, 2008, when Hensol Castle, at Hensol in the Vale of Glamorgan, posed as the CAL hospital. The next day was centred on Cardiff, beginning with work at Victoria Park for scenes at the playground with Donna and her children; unfortunately, heavy rains forced the postponement of much of the recording. Material in Charlotte's living room was taped at a residence on Palace Road, while the photo of Donna with her babies was shot at Crwys Medical Centre, and the picture of Donna and Lee's wedding was taken at St Mary's of Angels. Tate once again donned the wedding dress she had worn throughout The Runaway Bride for the occasion. On the 17th and 18th, two houses on Palace Road were employed, one for more sequences with Charlotte and another as Donna and Lee's house. The latter venue was visited again on the 19th, while the 21st saw additional scenes in Charlotte's living room filmed. Lyn's team also attempted to remount the playground material at Victoria Park on the 21st, but the weather again prevented the completion of the recording.

January 22nd took cast and crew to Dyffryn Gardens at St Nicholas in the Vale of Glamorgan, where additional sequences at the CAL hospital were taped, along with those in Donna's children's bedroom. Upper Boat Studios was the venue for the next three days, dealing with filming on the sets for the TARDIS and the shop (plus the effects sequence of crowds emerging from the Library computer) on the 23rd; the Bookcase Room, the lift platform, and various corridors on the 24th; and the Bookcase Room and more corridors on the 25th. By now it had been realised that, with Midnight having been moved after “Forest Of The Night”, consecutive episodes would now air with very similar titles. It was decided that a new name for the second part of Moffat's adventure would have to be found. The writer proposed a variety of alternatives, with Davies preferring “River's Run”. Moffat then amended his script to better justify the new title.

On January 28th, Brangwyn Hall in Swansea provided the Library's main entrance, while scenes in the facility under the Library were filmed in the Alcoa Emp Swansea factory at Waunarlwydd Works on the 29th and 30th. Cast and crew remained in Swansea for the story's major location: the recently-vacated Swansea Library, where sequences in the Blue, Red and Yellow Indices were recorded from January 31st to February 12th (omitting only February 3rd, 9th and 10th, and including insert shots of Charlotte's living room on the 11th). On February 1st, it was announced that Phil Collinson would be leaving Doctor Who following the completion of the season finale, The Stolen Earth / Journey's End, to become Head of Drama for BBC Manchester. Meanwhile, it had now been realised that Silence In The Library was running very short, and so Moffat quickly provided extra material, with the discovery of Miss Evangelista's body being the chief beneficiary.

In addition to the end of work at the Swansea Library, the team also spent part of February 12th back at Brangwyn Hall for the sequences in which Miss Evangelista wanders away and her body is subsequently discovered. This was completed the next day, when the footage of the Doctor, Donna and Lux looking out at the vastness of the Library was also captured. The 14th saw the playground scenes at Victoria Park recorded at last, while various effects and insert shots were taped at Upper Boat. The latter work continued on the 19th and 20th to conclude principal photography on the story.

In postproduction, executive producer Julie Gardner became unhappy with the title “River's Run”, and once again asked Moffat to devise a new name. The script was then briefly known as “Return Of The Dead” before Moffat -- who still preferred “Forest Of The Night” -- decided to merge the two titles and christened the episode Forest Of The Dead. On May 20th, in the lead-up to the broadcast of Silence In The Library, the BBC announced publicly that Moffat would be taking over from Davies as Doctor Who's showrunner. By this stage, Moffat was already in the midst of planning his first season with Gardner's successor, Piers Wenger.

• Outpost Gallifrey: New Doctor Who Series News Page, edited by Shaun Lyon.
• Doctor Who Magazine Special Edition #20, 19th November 2008, “Episodes 8 & 9: Silence In The Library / Forest Of The Dead” by Andrew Pixley, Panini Publishing Ltd.
• Doctor Who: The Writer's Tale by Russell T Davies and Benjamin Cook (2008), BBC Books, ISBN 978 1 846 07571 1.