It featured Yvonne Hartman for the first time in any medium since her television debut.
Yvonne Hartman is visiting the city to retrieve an invaluable alien device. She's in charge of Torchwood One, she's saving the British Empire and she doesn't care about local politics. But she is going to find herself caught up in that fight. There's a bloodthirsty alien stalking the streets and there's a special offer on at the all-you-can-eat Chinese buffet.
Yvonne stands in Roald Dahl Plass and calls Bev. Ianto answers instead and she has him tell Rajesh to activate the time bubble so that she can enter the Hub and steal a Drahvin scanner, planning to use it to find what is inside the sphere at Torchwood Tower. She does so, seeing Jack in the flesh for the first time.
Ross Bevan answers the phone to his lover, Ian, before creature that he believes to be someone in a costume enters. He is beheaded and his wife, Meredith, finds the body and calls the emergency services.
After losing the scanner in a fire at Manor Rest Hotel, Yvonne and Barry Jackson, who early told her that members of Cardiff Council were being murdered, go to a Chinese buffet. He tells her that it is candidates for mayor that are being beheaded and she calls one such person, Julie Jones, who is killed in the buffet's toilets during the call.
Yvonne and Barry go to meet with Helen Evans at the White Lion, talking about whether or not the public should know about the existence of aliens. Helen refuses to leave with Yvonne until a fight breaks out, leaving as a police sergeant arrives with PC Cooper and PC Davidson. Yvonne and Helen are chased by the creature and are joined by Barry.
Yvonne, Barry and Helen go to the Priory Nightclub, gaining access by blackmailing the bouncer, Mike, to keep safe from the creature. In the toilets, Yvonne promises to share alien technology with Helen should she become Mayor and keep an eye on what comes through the Rift. The creature attacks and, once outside, kills Helen and knocks Yvonne unconscious. Upon waking, she calls Ianto and has him supply her with money for a taxi and Barry's address.
At the Waterside Apartments, Barry admits to having murdered Roy Llewellyn, covering it up by blaming it on the Autons. Yvonne threatens to kill by brandishing a kitchen knife and forcing him up onto his balcony, making him tell her that he works for the Committee and was supplied with the creature by them. She agrees to let him live in return for him keeping an eye on Jack and for the arrival of the Doctor, although she stabs him in the leg to give him a limp to remind him that she is watching.
- Yvonne Hartman - Tracy-Ann Oberman
- Barry Jackson - Gareth Armstrong
- Helen Evans - Rebecca Lacey
- Ross Bevan - Dan Starkey
- Meredith Bevan - Catrin Stewart
- Ianto Jones and Raj Singh work as Yvonne's assistants at Torchwood One.
- Yvonne observes Jack along with Suzie Costello and Toshiko Sato in the frozen Hub. At this point, the three of them are the only members of the Torchwood Three team.
- Ross Bevan was born in 1968.
- Bevan is having an affair with Ian.
- Believing that the creature is a costume, Bevan asks if it is Sheila.
- Bevan is looking forward to the new series of Strictly Come Dancing.
- Meredith buys a Rioja because the shop, which used to be run by a "lovely" Indian family, did not have any Merlot.
- Berta is a masseuse.
- Yvonne tells Berta to grab the pinot before leaving the hotel.
- Some people are taken from Manor Rest Hotel to St Helen's Hospital.
- The reporter reports to Sian in the studio.
- Yvonne and Barry go to a Chinese buffet and have prawn crackers. He says that they will get chicken satay next.
- Cardiff is undergoing regeneration projects.
- Brian Rayner and Julie Jones are two of the councillors killed.
- Barry receives a call from Idris.
- The Auton invasion, brought forth by the Nestene Consciousness transmitting a signal to animate all plastic on Earth via the London Eye before it was defeated by the Ninth Doctor, occurred three weeks ago and had spread beyond London to at least Cardiff before it was stopped, where Barry used it as a cover for his murder of former Lord Mayor of Cardiff Roy Llewellyn.
- Noting Torchwood's absence in the Auton invasion to Yvonne, Barry notes that Torchwood has been there for the previous invasions along with UNIT and "the others".
- Colin is the barman at the White Lion on St Mary's Street.
- Helen is at the pub for her friend Karen's birthday.
- Barry suggests that Bar Reunion would best suit Yvonne. Helen instead suggests Priory Nightclub.
- Yvonne has tea with the Queen twice a week.
- Torchwood One were yet to start using spreadsheets when Yvonne joined.
- According to Yvonne, Jack Harkness does not have the interest of Torchwood at heart. Because of this, she requires Barry Jackson to keep an eye out for the return of a particular alien, as she knows Harkness will fail to notify her.
- Strictly Come Dancing is mentioned by one of the people in the restaurant. Yvonne calls it a fad, just as Charles and Camilla will be within a couple of weeks.
- Raheem is a taxi driver.
- Skip is a bartender.
- Yvonne tells Helen that she is a member of MI5.
- Yvonne compares Mike, the bouncer of the Priory Nightclub, to a Neanderthal.
- Yvonne tells Mike that her brother worked as a bouncer and read Voltaire.
- Barry lives at the Waterside Apartments.
- There is an outbreak of Marburg virus in Angola.
- This story was recorded on 11 September 2015 at The Soundhouse Studios.
- Yvonne says that this is the first time that she has met Jack.
- Gwen Cooper and Andy Davidson have one line cameos in this story, set two years before Gwen joined Torchwood Three in 2007.
- This story takes place on 26 March 2005, the same day that Series 1 of the revived series of Doctor Who premiered on BBC One.
- The title of the story can be viewed as a multi-layered pun. Not only is it the "one rule" of Yvonne Hartman, as explicitly stated in the story, but can also be read as a "rule of Torchwood One" or even the fact that the story depicts the period when Torchwood One ruled over Torchwood Three, which is also unequivocally depicted in the story.
- Although everyone is talking about the new series of Strictly Come Dancing, the 2005 series was broadcast beginning in October.
- This story was originally released on CD and download.
- Yvonne expects Bev Stanley to answer the phone. (PROSE: Trace Memory)
- Whilst talking to Ianto on the phone, Yvonne tells him to ask Lisa Hallett out. (TV: Cyberwoman)
- Torchwood One are attempting to ascertain the nature and purpose of the Void Ship. (TV: Army of Ghosts / Doomsday)
- Torchwood Three possesses a Drahvin scanner, which is procured by Yvonne. (TV: Galaxy 4)
- Yvonne says "Happy Day". (TV: Army of Ghosts)
- The Lord Mayor of Cardiff Roy Llewellyn was killed by the Auton invasion which reached Cardiff on 5 March 2005. (TV: Rose) He would eventually be succeeded by Blon Fel-Fotch Passameer-Day Slitheen, posing as Margaret Blaine. (TV: Boom Town)
- Both Barry and Helen, who are running in the mayoral race, moan about London's lack of interest in Cardiff. This is reminiscent of when Blon went "native" during her time as Lord Mayor. (TV: Boom Town)
- A cover story was concocted to explain away the invasion on 5 March as a "terrorist attack". Such measures were previously taken for the first Auton invasion in the 1970s. (PROSE: Who Killed Kennedy; TV: Spearhead from Space)
- Yvonne speaks of the incident on New Year's Eve 1999 involving the murder of the Torchwood Three team by its leader Alex Hopkins, who went mad after seeing the coming "change" in the 21st century before committing suicide. (TV: Fragments)
- Yvonne says that she is doing it "for Queen and Country" before downing a pint of Diamond White beer. She would maintain that she did her duty for Queen and Country immediately before her forced cyber-conversion during the Battle of Canary Wharf in 2007. (TV: Doomsday)
- Gwen Cooper and Andy Davidson are members of the Cardiff police force. (TV: Everything Changes)
- Yvonne says, "When I say 'run'..." (TV: The Tomb of the Cybermen, et. al)
- Yvonne tells Barry and Helen that she is a people person. (TV: Army of Ghosts)
- Skip Jameson was still working at the Priory Nightclub in 2009. (AUDIO: In the Shadows)
- Yvonne explains to Helen and Barry that Torchwood's presence in Cardiff is down to the space-time rift running through the city. (TV: The Unquiet Dead, Everything Changes) Yvonne states that alien objects and species come through the rift and that Torchwood seizes them and uses them to defend Britain. (TV: Army of Ghosts)
- Helen was born and raised in Splott. (TV: Ghost Machine, Random Shoes, et. al)
- Ianto manages to hack into a London Credit Bank ATM. (TV: The Runaway Bride)
- Barry is an enabler of the Committee. (AUDIO: The Conspiracy)
- Yvonne says, "If it's alien, it's ours". (TV: Army of Ghosts)
- Yvonne tells Barry that Torchwood is awaiting the return of one particular alien to Cardiff. (TV: Boom Town)