Iterations of I (audio story)

Iterations of I was the second and final story in the audio anthology The Fifth Doctor Box Set, produced by Big Finish Productions. It was written by John Dorney and featured Peter Davison as the Fifth Doctor, Matthew Waterhouse as Adric, Sarah Sutton as Nyssa and Janet Fielding as Tegan Jovanka.

Publisher's summary
The house on Fleming's Island had been left to rot. Ever since a strange and unexplained death soon after it was built, and plagued with troubling rumours about what lurked there, it remained empty and ignored for decades until the Cult moved in. As twenty people filled its many rooms, the eerie building seemed to be getting a new lease of life.

But now it is empty again. The cult found something in its corridors... and then vanished.

Trapped on the island one dark night, the Doctor, Tegan, Nyssa and Adric look into the building's mysteries, its stories of madness and death. Their only chance is to understand what terrible thing has been disturbed here... before it consumes them utterly.

Part one
In August 1981, students Imogen Frazer and Martin Tuck take part in research on Fleming's Island off the coast of Ireland and Martin starts repeatedly saying i. Imogen fails to return to England so, in December, her boyfriend Jerome Khan travels to Ireland and reports her disappearance Constable Robert DeValley, who knows the island as a place of evil and decides to take a boat there.

Although Tegan is now happy to travel in the TARDIS, Adric and Nyssa attempt to program the ship to take them to Heathrow Airport in 1981 as a test whilst the Doctor is reading Black Orchid in the library. They land on top of a cliff on Fleming's Island and, after the four travellers exit, the ship falls to the ground below and a storm hits. Looking for shelter, they go to a nearby mansion outside of which is a smashed boat. They enter and Nyssa suffers from a psychic shock as her mind is momentarily flooded with numbers and voices.

Tegan stays with Nyssa, who repeatedly says i for a time, and finds a scrapbook which includes a newspaper article on the unexplained death of Sinead Fleming in the library. The Doctor and Adric find a smashed radio and go to repair the generator, passing a series of gravestones including Martin's, and are held at gunpoint after finding the body of a gunshot victim. One of several computers boots up in the house and shows the letter i; despite Nyssa's protests, Tegan presses the return key.

Part two
Robert makes Aoife lower her gun. Jerome informs them that he and Donal have found two women and the three of them take the Doctor and Adric back to the mansion, on the way to which the Doctor has a psychic shock and sees images of people screaming and being torn apart by the air. The two groups exchange information, with the four travellers learning that a cult based on the island has disappeared; the cultists believe that God is an impossibly long number and hired Imogen to try to calculate it so they could change the world.

Aoife screams when she sees a face in the window which Adric and Tegan have also seen and most of the group go to investigate whilst Adric and Nyssa attempt to repair the radio. Adric notices that the computer that Tegan used is generating numbers and repeating i and interpolates it with equations of his own, which gives the impression that something is moving through the numbers. He and Nyssa both start saying i.

From Imogen's tapes, the Doctor learns that there is something alive in the numbers, that Martin died after pressing the enter key on a computer flashing the letter i and that another man shot himself after attempting to interact with it. The computers are impossible to destroy or switch off. After Tegan tells the Doctor that she interacted with the computer, they hurry downstairs and manage to stop Adric, but Nyssa and Aoife continue to repeat the letter. Donal shoots the computer and they pass out, but all of the computers flash the letter and Donal is torn apart by the air.

Part three
The Doctor wakes Nyssa and Aoife with smelling salts and tasks them with checking the mast so that the repaired radio can be used to get help. He realises that the threat is a sentient number which has been locked into the imaginary number i and believes that it is killing people in different ways as it attempts to find a way to communicate. The visions have simply been ripples on the surface of the world. Adric manages to trap the i and find a way to speak with it; it says Jerome's name and the name of the pub where he met Imogen.

The Doctor deduces that Imogen has become a sentient number, but the group are kept from doing anything more when Robert holds them at gunpoint and demands that Adric hands him the number to be used to manipulate the stock market. After Adric gives him a floppy disk, he shoots Adric in the leg to ensure that the group allow him to leave and take him to a hospital on the mainland. Robert barricades the door as he leaves with Adric to contact the outside world and the Doctor realises that the i wants to be set free before it is caught by a predator; he releases the i, but the predator kills Aoife.

Part four
The Doctor decides to try to defeat the predator by blinding it with data and sets up a generator to produce random numbers to attract it. He also explains that Sinead Fleming was likely killed by her husband, who entered and escaped the locked library using a trick window. The computers explode and the mansion is severely damaged, but the Doctor, Nyssa, Tegan and Jerome get out and attempt to keep Robert from leaving the island with Adric in a helicopter piloted by a colleague.

Thanks to his Alzarian constitution, Adric's leg quickly heals and he escapes the helicopter, falling back to the island and suffering from nothing more than a limp. The predator enters the helicopter and causes it to crash, killing Robert and Joe. Tegan, having seen a map, leads the way down to the TARDIS and Jerome realises that Imogen, whom he has a copy of on a disk, deliberately became an i to survive. Imogen turns him into an i and the Doctor attempts to use a calculator to confuse the predator before heading into the TARDIS, which the predator starts to devour. The i are able to take it, however, and thank the Doctor.

The Doctor changes the frequency of the TARDIS scanner, allowing him and his companions to watch as the i trap the predator in a mathematical whirlpool created by the feedback loop of the calculator. He starts piloting the ship, theorising that Adric using negative numbers instead of positive ones was what brought them to Fleming's Island. Adric leaves the control room, feeling that what has happened is his fault and that nobody takes him seriously, and the TARDIS dematerialises.

Cast

 * The Doctor - Peter Davison
 * Tegan Jovanka - Janet Fielding
 * Nyssa - Sarah Sutton
 * Adric - Matthew Waterhouse
 * Aoife Dineen - Sinead Keenan
 * Jerome Khan - Joseph Radcliffe
 * Robert DeValley - Andrew Macklin
 * Donal Dineen - Teddy Kempner
 * Imogen Frazer - Allison McKenzie
 * Martin Tuck - John Dorney

Worldbuilding

 * The computers in the house on Fleming's Island have a capacity of two Megahertz. The Doctor correctly dates them to the early 1980s.
 * The Fifth Doctor believes that numbers have no existence on their own, and only exist in relation to other things.
 * Jerome Khan studies English while his girlfriend Imogen Frazer studies Maths. Both attend university in London.
 * Tegan describes the Doctor and Adric's bickering as "the 'Elementary, Dear Watson' routine."
 * Tegan refers to the Loch Ness Monster.
 * Neither Tegan nor Nyssa believe in ghosts.
 * Branwell Damien Fleming was born in 1878 and died in 1935.
 * Sinead Iona Fleming was born in 1905 and died in 1930.
 * Martin Tuck was born in 1962.
 * In 1980, a cult, which believed that God was an impossibly long number, took up residence on Fleming's Island.
 * DeValley refers to Adric as "pyjama game."

Continuity

 * Adric refers to the fact that he once piloted the TARDIS (TV: The Visitation) while Tegan reminds him that she once did as well. (TV: Castrovalva) In piloting it, Adric activates the Synchronic feedback circuit. (TV: The Pirate Planet)
 * The Doctor is in the TARDIS library reading Black Orchid by George Cranleigh, which was given to him by the author's mother Lady Madge Cranleigh on 11 June 1925. (TV: Black Orchid) He would later describe it as being very interesting. (TV: Earthshock) His sixth incarnation was less fond of the book, later describing it as "a Boy's Own adventure about an aristocrat who yomped through the Brazilian rainforests, depriving the natives of their orchids." (AUDIO: Year of the Pig)
 * Adric attempts to materialise the TARDIS at Heathrow Airport in 1981, as the Doctor had failed to do on numerous previous occasions. (TV: Four to Doomsday, Kinda, The Visitation; AUDIO: Psychodrome, Smoke and Mirrors) He would later attempt it again after another argument with Tegan. (AUDIO: The Contingency Club)
 * Adric refers to the Logopolitans' use of computers to warp space-time. (TV: Logopolis)
 * The Doctor laments the destruction of his sonic screwdriver by the Terileptil leader in September 1666. (TV: The Visitation)
 * Nyssa refers to the death of her father Tremas at the hands of . (TV: The Keeper of Traken)
 * Tegan tells the Doctor that she has not been able to keep up with him since he had "curly hair and a scarf." (TV: Logopolis)
 * Tegan refers to Agatha Christie. During his tenth incarnation, the Doctor and Donna Noble met Christie at Eddison Manor on 8 December 1926. (TV: The Unicorn and the Wasp)
 * Adric refers to the fact that Alzarians heal much more quickly than humans. (TV: Full Circle, The Visitation)