The third series' episodes worked with a higher budget, and it was transferred to the network's flagship channel, BBC One, as a five-episode serial titled Torchwood: Children of Earth.

[8][9] This idea, originally titled Excalibur, was abandoned until 2005, when BBC Three Controller Stuart Murphy invited Davies to develop an after-watershed science fiction series for the channel.

[18] Although Torchwood was originally intended to be sci-fi aimed at adults, the character Captain Jack Harkness, who had previously been introduced in Doctor Who, proved popular with young audiences.

[39] Shortly after the broadcast of Miracle Day in March 2012, the chief executive officer of Starz, Chris Albrecht, announced that he was remaining in touch with the BBC regarding a further series of Torchwood, though it would depend on Davies being free from his other commitments.

The series is set in Cardiff, Wales, and follows a rogue covert agency called Torchwood which investigates extraterrestrial incidents on Earth and scavenges alien technology for its own use.

Series three, a miniseries, saw the Cardiff headquarters destroyed and the team temporarily operating as fugitives in England's capital city of London, its membership declining and the organisation thoroughly broken over the course of the serial.

The group is then unofficially reformed, this time operating primarily in the United States, joined by two fugitive CIA agents who have been framed for treason, during Miracle Day.

The team is made up of five operatives led by Captain Jack Harkness (John Barrowman), formerly a time-traveling "Time Agent" and con man from the distant future who has lived on Earth as an immortal since the 19th century.

Gwen Cooper (Eve Myles), the female lead, joins the team in the first episode; she is originally an audience surrogate, but later grows into a more morally complicated character.

The original cast is filled out by Torchwood medical officer Owen Harper (Burn Gorman), computer specialist Toshiko Sato (Naoko Mori), and general factotum-cum-administrator Ianto Jones (Gareth David-Lloyd).

Kai Owen becomes a main cast member in the programme beginning with the third series; his character is initially unaware of Gwen's activities with Torchwood but later becomes her close confidant and the team's ally.

Prior to the programme's debut, publicity materials featured Indira Varma as Suzie Costello among the regular cast members, giving the impression that she would appear throughout the series.

Other recurring characters include Doctor Who's Martha Jones (Freema Agyeman)—like Jack, a former time-traveller, and now medical officer for the militaristic alien-investigating organisation UNIT—who crosses over into Torchwood for three episodes in series two.

[70][71] Others in the second series, recurring in a minor capacity, include a mysteriously age-immune little girl (Skye Bennett) and Victorian-era Torchwood member Alice Guppy (Amy Manson).

Children of Earth featured a largely new supporting cast for the duration of the five-episode serial, such as Permanent Secretary John Frobisher (Peter Capaldi), Clem McDonald (Paul Copley), Frobisher's personal assistant Bridget Spears (Susan Brown), Prime Minister Brian Green (Nicholas Farrell), ruthless operative Agent Johnson (Liz May Brice), Jack's middle-aged daughter Alice (Lucy Cohu), her son Steven (Bear McCausland) and Ianto's sister Rhiannon (Katy Wix).

New to the Torchwood team are CIA agents Rex Matheson (Mekhi Phifer),[74][75] and Esther Drummond (Alexa Havins),[76] and surgeon Vera Juarez (Arlene Tur).

Nana Visitor plays Olivia Colasanto, who directs the team toward their real enemies; Frances Fisher and Teddy Sears portray recurring villains.

A three-episode arc ("Reset", "Dead Man Walking" and "A Day in the Death") in the middle of the series guest stars Doctor Who actress Freema Agyeman as Martha Jones, temporarily drafted into Torchwood.

The second series finale, "Exit Wounds", features the departures of main characters Owen and Tosh, whose deaths at the hands of Jack's long-lost brother Gray reduced the cast to Barrowman, Myles and David-Lloyd in its closing scenes.

The series focuses on the consequences of appeasement policy; having been given 12 children as a tribute in 1965, aliens called the 4-5-6 arrive in the present demanding a greater share of the Earth's child population.

The origins of the Miracle Day conspiracy are revealed in a 1920s flashback in "Immortal Sins", as the worldwide scale of the story takes the protagonists to Shanghai and Buenos Aires in the finale "The Blood Line".

[84] Conservative MP Michael Gove described the debut of Torchwood as the moment confirming "Wales' move from overlooked celtic cousin to underwired erotic coquette".

On the first website (for series 1), the alternate reality game was mostly composed of weekly updates to the site in the form of fictional intercepted blogs, newspaper cutouts and confidential letters and IM conversations between members of the Torchwood Three crew.

As with most other online video content from the BBC, Captain Jack's Monster Files are not viewable outside the UK and to date (2011) have never been included on a DVD or Blu-ray release of either Doctor Who or Torchwood.

The new series of audio dramas will each focus on different members of the Torchwood team, exploring the impact that a mysterious event has on them, taking place at various times in and around the TV episodes.

New to the series were civil servant St John Colchester (Paul Clayton), Ng (Alexandria Riley), news reporter Tyler Steele (Jonny Green), shapeshifting alien Orr (Samantha Béart), and a parallel universe version of Yvonne Hartman (Tracy-Ann Oberman).

[132] Conversely, The Daily Mirror gave the mini-series a negative review, describing it as "the modern-day Blake's 7: ludicrous plot, hammy acting, an adolescent penchant for 'Issues'".

[144] Satirical impressionist television series Dead Ringers also parodied Torchwood, with Jon Culshaw playing Captain Jack and Jan Ravens as Gwen Cooper.

[147] Later spoofs in the final episode of the 2007 series of Dead Ringers featured Jack Harkness in a threesome with two Attack of the Cybermen-era Cybermen, and an elderly version called Driftwood, which claims to be "separate from the Post Office, beyond the bingo hall and outside the Oxfam", a parody of Torchwood's opening narration.

It dropped to a low of 2.52 million viewers towards the end of its run,[148] even after the BBC had moved it from its usual Wednesday-night slot (where it was being consistently beaten by ITV's programming and Channel 4's number-one series, Grand Designs) to Friday nights.