The Doomsday Chronometer (audio story)

 was the third story in the audio anthology Doom Coalition 3, produced by Big Finish Productions. It was written by Matt Fitton and featured Paul McGann as the Eighth Doctor, Nicola Walker as Liv Chenka, Hattie Morahan as Helen Sinclair and Alex Kingston as River Song.

Publisher's summary
While River Song takes Helen on an archaeological expedition like no other, the Doctor finds himself enlisted by an alien Queen to save her people.

Trapped and alone, Liv stares death in the face as she meets the enemy who's been dogging the TARDIS travellers' footsteps throughout Earth's history.

The Doomsday Chronometer has been protected for five centuries: secret cults and societies jealously guarding its mystery. But what is their real purpose? The Doctor is about to discover the truth...

Plot
Mr Whitman tells Helen that the world is ending when they are separated by a group of nuns, one of whom approaches Helen and is revealed to be River. Using her vortex manipulator, she teleports the two of them away, saying that she is a "much better driver" than the Doctor.

The Doctor is stopped by Cromwell's guards and returns to his cells in an attempt to convince them that he is not trying to escape. Nonetheless, Cromwell has him taken to Tower Green to be executed.

The Clocksmith has the Solvers take Liv to a cauldron of molten lead, but she stops him by asking for an explanation. He tells her that he came for the Syran metal to make the Doomsday Chronometer, but found before even beginning that the clock would be separated across time. He has demanded the ticket so that, once he has made the clock, he can reassemble it. He then has Liv taken to the cauldron.

Helen and River arrive in 17th century France, near Rennes-le-Château. River explains that she is wearing a psychic wimple so that the Doctor will instead see her as a woman not unlike Rita Hayworth. River explains that the castle has recently been rebuilt by the Knights Templar and that she and Helen should go and do some archaeology.

Cromwell orders his guards to leave himself alone with the Doctor before his execution and tells him that he received a visit from an emissary from the Pope who paid to speak to the Doctor. He is taken to speak to her and learns that she is a Solver called Lady Risolva.

River tells Helen that the castle was built by the Revelation Sect, who began in the mid-15th century, and leads her in through a secret passageway. In a study, they find a list of paintings of interest to the sect in which River believes there is a code and teleport away before they are found by the guards. The Clocksmith asks them what has happened. River destroys a painting and, when the alarm sounds, teleports herself and Helen to Leonardo da Vinci's studio where they collect the relevant paintings. After they leave for Temple Church in Fleet Street, da Vinci runs in and rues "that woman".

Lady Risolva tells the Doctor and Cromwell that she came to see the Doctor to save her people, who were taken away from their planet by the Clocksmith. A cart carrying the TARDIS arrives.

In May 1941, River smashes an 18th century stained-glass window restored by "Veronica Settle" (an anagram of "Revelation Sect") and finds a key embedded in the frame. She and Helen teleport away as the church is hit by a bomb.

Cromwell has his men push the TARDIS the right way up and wonders with the Doctor who sent it, with the Doctor suggesting Abbot Malvern. He bids farewell to Cromwell, saying that he will let history run its course where he is returned and that he is sorry. Lady Risolva thanks Cromwell for his assistance and enters the TARDIS with the Doctor. Brother Octavian tells Cromwell that he brought the TARDIS as the Doctor was the only one that could help and agrees to write an account of the Doctor's escape and death before returning to his meditation. Cromwell decides to leave for Flanders to find a bride for Henry VIII and put aside thoughts of the supernatural.

Having created a map using the straight lines of Leonardo's paintings in the Louvre Pyramid, River and Helen go to the catacombs beneath the Vatican in the 1960s. River uses her sonic screwdriver to restore the key and warns Helen that she will not be able to use her vortex manipulator due to the lining of the catacombs. The Clocksmith, addressed as a cardinal, is told that there has been a breach in security by "the nun" and hurries towards the inner chamber. River and Helen reach the sanctum and take the eighth piece of the Doomsday Chronometer before running.

In the TARDIS, Lady Risolva tells the Doctor that the Clocksmith found a way to control her people and that she had to reconstruct herself after being disassembled. They begin heading to Prague, the last place that Risolva had any trace of her people, and the Doctor finds that the Clocksmith's TARDIS has been moving throughout European history.

River and Helen run from the Clocksmith's guards and manage to escape once free from the damper field. The Clocksmith, angry, uses his device to kill one of his guards and questions who the nun is and where in history he needs to be. Back in Rome 2016, River tells Helen to go to the Science Museum and insert the eighth piece into the Doomsday Chronometer after her past self meets River. River says to herself that it is time to go back to the start before teleporting away.

As the Clocksmith is about to kill Liv, River appears and, although unable to destroy the Solvers, threatens to shoot him. The Clocksmith releases Liv and the Solvers say that they can hear their queen, making them reject the Clocksmith's leadership and attack. The room catches fire, destroying the Clocksmith's paintings, and he escapes in his TARDIS. River takes a piece of the Doomsday Chronometer before teleporting away with Liv.

The Solvers put out the fire on Lady Risolva's orders and tell her and the Doctor that "Malone" and Liv had escaped. The Doctor chooses not to try to restore the clock due to the established timeline and asks Lady Risolva to have her people hide them across Earth, leaving hints and clues which will take the Revelation Sect five centuries to solve. He leaves to find Helen.

Helen meets "Professor Salvatore" and shows him the eighth piece, which she surmises was kept by the highest level of the Revelation Sect so that they would always hold the key to its completion. He tells her to complete the Doomsday Chronometer whilst Rosalia refuses entry to Mr Whitman, who says that she must not complete it.

River and Liv arrive in 2016 Rome. River uses her sonic screwdriver to open the museum door and meets Mr Whitman, who tells her that he was once Osm and Brother Octavian. He tries to take the piece from River. Helen completes the Chronometer and is told by Professor Salvatore to wait. He takes out his device, making her realise that she has "backed the wrong horse". River, Liv and Mr Whitman enter the museum and the TARDIS arrives. River sends Rosalia to evacuate the museum and introduces herself to the Doctor as "Sister Cantica".

The Clocksmith tells Helen that there is a ninth piece to the Chronometer and uses his device to hold her in place as a bargaining chip as the piece approaches. The Doctor and Lady Risolva head to the Chronometer whilst the Solvers keep River and Liv back for their safety. Mr Whitman says that he has to tell them both something. The Doctor and Lady Risolva reach the Clocksmith, who uses the Chronometer's power to tear Lady Risolva apart, and River reveals that the spring that she took from the workshop is the ninth piece.

River, Liv and Mr Whitman go to save the Doctor. The Clocksmith tells them that he made the Chronometer as a small contribution to "the cause" of the Coalition, made from the first world destroyed in the Sonomancer's name. River hands over the ninth piece to save the Doctor and Helen. The Doctor tells Liv and Helen to run and watches as the Chronometer begins ticking, forcing coordinates into the Doctor's head whilst Mr Whitman gets clarity and reveals himself to be a Time Lord. The Solvers are restored and march on the Clocksmith, taking apart the Chronometer, whilst the Doctor, River and Mr Whitman launch a psychic attack. The Clocksmith apparently kills Mr Whitman with his device and he is ripped apart by the Solvers.

The Doctor's mind is swamped by the coordinates and River helps him to safety in the Clocksmith's TARDIS. Lady Risolva tells them that the Solvers will take the pieces of the Chronometer and make sure that it is never put together again. River pilots the TARDIS away, reminding the Doctor that a group of Time Lords are trying to harness a resonant power when he begins talking about Rita Hayworth. Liv and Helen watch the museum crumble.

The Eight emerges from the rubble and enters the Doctor's TARDIS, the voices of his former selves shouting in his head as he says that he is a good and peaceful man. He begins his regeneration.

The Doctor and River use the fast return switch, taking them back to the Tower of London where they discuss how the completion of the Chronometer meant that doomsday would now come about. He chooses not to go back for Liv and Helen and to instead save the universe with River, hoping to keep them safe.

Liv and Helen enter the TARDIS, where Mr Whitman completes his regeneration into his next incarnation. He asks Liv and Helen, who believe that he is the Doctor, how he looks.

Cast

 * The Doctor - Paul McGann
 * Liv Chenka - Nicola Walker
 * Helen Sinclair - Hattie Morahan
 * River Song - Alex Kingston
 * Thomas Cromwell - John Shrapnel
 * Solvers - Glen McCready
 * Rosalia - Emma D'Inverno
 * Octavian - Tim McMullan
 * The Clocksmith - Nicholas Woodeson
 * Risolva - Janie Dee

Continuity

 * The destruction of the planet Syra is mentioned. (AUDIO: The Sonomancer)
 * The Clocksmith watched the Doctor, Liv and Helen give the piece of the Doomsday Chronometer to Midge. (AUDIO: Absent Friends)
 * The Doctor mentions Abbot Malvern. (AUDIO: The Eighth Piece)
 * River mentions she knew another Octavian once, who was part of another church. (TV: The Time of Angels)
 * Liv recognises River as Professor Malone. (TV: The Angels Take Manhattan, AUDIO: The Sonomancer)
 * River tells Helen to have the Doctor take her to Versailles one day, but to avoid Madame de Pompadour. (TV: The Girl in the Fireplace)
 * The Clocksmith refers to River as an Interfering Nun. (PROSE: Shada)