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The Sontaran Stratagem was the fourth episode of series 4 of Doctor Who.

It was the first appearance of the Sontarans in the revived series and saw the reappearance of Martha as a recurring guest character following the next two episodes.

Also of note was the casting of the Sontarans. As well as featuring the return of Christopher Ryan in a new role, this episode featured the first Doctor Who appearance of Dan Starkey, seen here as Commander Skorr. Primarily recognised later as Commander Strax, a friend of the Doctor, he would go on to appear in various other roles, several of them also Sontaran, in both the TV series and Big Finish Productions' audio dramas during the years that would follow.


Fifty-two people across the world in eleven different time zones die at the exact same time. The only connection: they all have ATMOS installed in their vehicles. Martha Jones, now a UNIT medic, summons the Tenth Doctor back to modern-day Earth to help figure out why, but an old enemy lies in wait...


Luke Rattigan and his students toss out reporter Jo Nakashima and her notes from the Rattigan Academy. She protests, saying that she's investigating ATMOS, Rattigan's invention, which she believes is dangerous. An uninterested Rattigan lets her leave. However, he goes inside and contacts his mysterious employer, recommending Jo's termination. His employer reminds him they don't take orders from "humans", but Rattigan reminds him that he said "recommend", and the employer agrees to terminate Jo.

Sometime later, Jo is in her car, which is fitted with ATMOS. She leaves a message for Colonel Mace of UNIT, asking him to check out several recent deaths that have happened in ATMOS-equipped cars and to pinpoint the times. At the same time, she follows her ATMOS's instructions. After crossing a bridge, the car turns right and stops at the bank of a river. Jo is confused, as she told ATMOS to take her to UNIT Headquarters. She's about to find her own way when the car doors lock themselves and the transmission of the car locks itself in the drive position. The car accelerates towards the bank. Jo screams as the car goes flying, landing in the river, where it sinks with her inside, causing her to perish.

Meanwhile, Donna is flying the TARDIS with mixed results while the Tenth Doctor watches closely, warning her not to get too close to the 1980s. Donna sarcastically wonders if she's going to put a dent in them. The Doctor mutters to himself "Well, somebody did." He gets a call on his mobile phone, from former companion Martha Jones. Donna is confused that the Doctor has a phone, to which the Doctor says it's not his; he answers, getting a happy Martha on the other line. She tells him that she's bringing him back to Earth.

Martha waits in an alley when the TARDIS materialises. The Doctor introduces Martha and Donna, asking them to not to start fighting. However, both Martha and Donna get along by making jokes about him. Donna congratulates Martha, holding up Martha's hand to the Doctor to show a ring on her finger. Martha says she's now engaged to Tom Milligan and, thanks to the Doctor's recommendation, has a job with UNIT as a medical officer. She speaks into a walkie-talkie and gives the all-clear to execute "Operation Blue Sky." Elsewhere, UNIT forces raid an ATMOS factory and capture the workers. What no one knows is that Luke Rattigan's employer is watching the raid on a television monitor and is not very impressed.

Martha leads the Doctor and Donna into a lorry containing a mobile UNIT headquarters. She introduces the Doctor to Colonel Mace, who knows about the Time Lord from UNIT files. The Doctor isn't impressed either with the overly military "new" UNIT or their handling of civilian workers in the ATMOS factory. Donna compares it to how the United States treats detainees at Guantanamo Bay.

Martha and Mace explain why they've executed the raid: just the day before, fifty-two people were simultaneously poisoned to death in their cars across the world. Martha has checked the biopsies and found the unknown toxin had left each of their bodies immediately. The cars in question are of different makes and models but are all fitted with ATMOS. UNIT suspects that the technology is alien in origin.

Meanwhile, two UNIT soldiers, Privates Harris and Gray, are exploring in the lower corridors of the ATMOS factory. Wandering into another corridor, they find two ATMOS workers guarding a door. Rattigan's employer remotely orders the two workers to let the soldiers in. Hypnotically, one opens the door. They enter a room with mysterious lighting and a tank with something banging underneath. They figure it must be a cloning tank and someone is growing a body. Gray tries to call for backup, but a squat armoured person appears in the room and praises Harris's skills of deduction. He tells Gray that he smells of sweat and fear. After Harris calls him "Humpty Dumpty", the figure fires a bolt of energy from a staff to disable Harris's legs. Gray fires his submachine gun, but it only clicks. The figure reveals that the room is contained within a cordolaine signal that excites the copper surface of the bullet and causes expansion in the barrel, rendering their guns useless, as well as blocking their radio signals, during which time Gray tries using his pistol but finds that is also useless. Gray raises the submachine gun to strike a blow and the figure fires at Grey's legs, causing him to fall the floor as well. When asked for a name, the figure identifies himself as General Staal of the Tenth Sontaran Battle Fleet, known as "Staal the Undefeated." He takes off his helmet to reveal a face that horrifies the disabled privates.

The Doctor examines the ATMOS equipment and concludes it is advanced but not alien technology. He notes that he didn't expect Martha to work for the military, but she points out that he left her and she is working with UNIT on her own terms. Donna has been using her own skills to go over the personnel records. She returns with the Sick Days file, which is empty. There have been no sick employees at the factory in months, if ever, which is more suspicious. The Doctor wants to go see Luke Rattigan, the creator of the ATMOS system. Mace assigns him a private, Ross Jenkins. Meanwhile, Donna and Martha chat and Martha notes that her family suffered because Martha didn't tell them about her involvement with the Doctor.

In the basement, Staal finishes the hypnotic programming on Gray and Harris, assigns them orders and returns to the Sontarans' ship via a teleport pod. The Doctor prepares to go the Rattigan Academy and Donna says that she's going home. The Doctor thinks she means she is leaving for good. He babbles on about how he'll miss her until he figures out she's just going home to talk to her mother and granddad. Meanwhile, Martha talks to a factory worker, Trepper, who seems to have come from Poland just to work. She finds him little more than an automaton with a rapid heartbeat, as he speaks in an emotionless monotone and he claims he works 24 hours a day. She goes to find Mace. Gray and Harris offer to escort her to the colonel. They take her to the basement and lock her in the cloning chamber.

Donna returns home and explains to Wilfred where she's been; she learns that it's been a few days since the Adipose incident. He takes it well but warns her not to tell her mother, Sylvia. When Sylvia comes in and demands to know where Donna has been, Donna says she's been travelling. Sylvia mocks Donna for gallivanting around and scolds her for the trick with the keys; she did find them.

The Doctor and Jenkins travel to the Rattigan Academy, and the Doctor notes that even UNIT jeeps have ATMOS. Jenkins says that until the system has been proven dangerous, the government refuses to remove ATMOS. They arrive at the academy and meet Luke. The Doctor checks out the science labs and goes to Luke's reception area, which contains a large piece of tunnel-like sculpture. The Doctor notes that Luke couldn't have created the equipment in the science labs. He triggers a control on the piece of "art," revealing it's a teleport pod.

The Doctor stumbles upon the Sontarans

The Doctor ends up teleporting the Sontaran spaceship. As they notice him, he teleports back. General Staal makes it through before the Doctor can sabotage the pod. He removes his helmet. The Doctor, realising who he's up against, taunts Staal about his honour and bounces a ball off of the wall behind Staal. It hits his probic vent, the Sontarans' one weakness. Staal, stunned, collapses. The Doctor and Jenkins make their escape. Staal recovers and fixes the teleporter, then returns to his ship with Luke. He has his second-in-command Commander Skorr, "the Bloodbringer", begin the invasion.

Skorr teleports down to the factory and confronts a captured Martha, saying for her, they need something more sophisticated than the hypnotic programming they utilised in the factory drones and the privates. He renders her unconscious and begins transferring her memories into a clone.

Luke suggests using the ATMOS to kill the Doctor, confusing Staal; Luke had told him that the Doctor had not given his name. Staal recalls that legends of the Last Great Time War said that the Doctor led the Time Lords into battle. He becomes elated at the idea of wiping out the last Time Lord along with Earth. He tracks the Doctor through the ATMOS device in the jeep and drives it into the river. The Doctor overrides the device by reverse psychology: he orders it to do what it's doing anyway so it will disregard his orders and do the opposite. It stops just short of the river and the Doctor and Jenkins jump out, expecting an explosion, which turns out to be unnecessary as the ATMOS just sparks and shorts out. With the ATMOS destroyed, Staal assumes that the Doctor is dead and confirms with Skorr that the Martha clone is ready. Luke assures him that the initial test run resulting in the fifty-two dead car drivers was successful and they are ready to unleash ATMOS on a wider scale.

The Doctor goes to pick up Donna while Jenkins finds a vehicle without ATMOS so they can get back to UNIT. Wilfred comes out to meet the Doctor only to find the same man who disappeared in front of him on Christmas Eve. However, he takes this and the knowledge the Doctor is an alien in his stride and the two men introduce themselves properly. Sylvia however is less impressed to find the person who caused so much trouble at Donna's aborted wedding. The Doctor calls UNIT and talks to the Martha clone. She promises to pass on his warning about the Sontarans but tells Mace that everything is fine. The Doctor then examines the ATMOS in Donna's car and triggers a hidden device exposing gas nozzles. The Sontarans detect the activation and Staal realises the Doctor is still alive. He is delighted, looking forward to a glorious battle, and orders the invasion to begin and the Sontaran ships close in.

The Doctor realises the gas is poisonous and there are over four hundred million cars on Earth with ATMOS. Wilfred tries to move his car, but at the same time, Staal orders the converters to be activated and every one deadlocked. As Wilfred gets in his car, the doors suddenly lock themselves and the engine starts. As the ATMOS device begins to emit a poisonous gas, the Doctor tries to disable the ATMOS to get Wilfred out. In a supermarket car park, every ATMOS car goes crazy, releasing the same gas while their owners attempt to stop them. At UNIT, soldiers try to destroy their ATMOSes by shooting at them. Mace learns that all other cars equipped with ATMOS have been activated.

Meanwhile, the Doctor's efforts to get Wilfred out of his car fail. He is interrupted when the gas starts setting off car alarms on the street. He looks up to see other parked cars emitting the gas. Up above, the Sontarans and Rattigan shout a war chant as the invasion begins.


Uncredited cast[]


General production staff

Script department

Camera and lighting department

Art department

Costume department

Make-up and prosthetics



General post-production staff

Special and visual effects


Not every person who worked on this adventure was credited. The absence of a credit for a position doesn't necessarily mean the job wasn't required. The information above is based solely on observations of the actual end credits of the episodes as broadcast, and does not relay information from IMDB or other sources.


Diseases and illnesses[]

  • Donna is surprised that no ATMOS employees have ever had man flu.




  • The Doctor mentions the fifteenth broken moon of the Medusa Cascade.
  • Streets in Chiswick include Rydale Street and Mallard Street.


  • The Doctor mentions Cotter Paluni's World as one of the planets he wanted to take Donna.
  • The Doctor also mentions wanting to take Donna to the Diamond Coral Reefs of Kataa Flo Ko.


Time wars[]


  • The Doctor said he worked with UNIT some time in the 1970s, "or was it the 80s?"

Unified Intelligence Taskforce[]

Story notes[]

  • The Doctor last saw Martha Jones in the television story Last of the Time Lords. It is not indicated on screen how long it has been for Martha since she last saw the Doctor, although it has been long enough for her to have joined UNIT, obtained her doctorate, become engaged to Tom Milligan and worked with Torchwood. Martha last appeared (chronologically) in A Day in the Death.
  • The Sontarans first appeared in the television serial The Time Warrior and last appeared on a TV broadcast in The Two Doctors, though they did feature in a direct-to-video story, Shakedown: Return of the Sontarans. They also feature in the television stories The Sontaran Experiment and The Invasion of Time. Though physically similar to prior appearances, their uniforms are now blue (though a few Sontarans seen aboard their command ship are seen in armour coloured more like previous versions; however, they still have blue helmets and shoulder pads) and their voices have taken on a more human quality. They are honourable when it comes to the rules of warfare and respect their enemies, but are callous and bloodthirsty.
  • Helen Raynor wrote this episode. Her Series 3 episodes Daleks in Manhattan and Evolution of the Daleks both filled fourth and fifth episode slots in the series. This two-part story also occupies episode four and five.
  • Helen Raynor was originally reluctant to write this story, having read online comments about her previous Dalek two-parter and come away "physically shaking" at the level of vitriol. Russell T Davies convinced her not to take the comments too seriously and to write this story. (REF: The Writer's Tale)
  • This two-parter is Douglas Mackinnon's debut story as the director.
  • When Donna asks the Doctor if it was his influence that turned Martha into "a soldier", a few notes of Donna's theme music can be heard before it segues into the music which plays when the UNIT soldiers appear.
  • Mobile phone company O2 released an ATMOS SatNav phone, possibly based on the devices used in this episode.
  • This show was broadcast during the thirty-fifth anniversary year of the Sontarans.
  • In The Time Warrior the Sontarans were described as "nasty, brutish and short", a reference to Thomas Hobbes. This is the first time that they are shown to actually be shorter than normal human stature.
  • There is a UNIT character called Jenkins, a homage to a famous piece of dialogue: "Jenkins, chap with the wings there Five rounds rapid" from the television story The Dæmons. In the commentary broadcast on BBC7, it was said that "Jenkins" was named for Richard Jenkins, who maintains the BBC's DW website.
  • UNIT has now been rebranded as the Unified Intelligence Taskforce, having previously been known as the United Nations Intelligence Taskforce. This followed a request by the United Nations shortly after the series returned to TV in 2005. Nonetheless, Martha still refers to UNIT receiving funding from the United Nations and the latter Children of Earth: Day One indicates that the UN still commands UNIT.
  • When communicating with each other, UNIT use call signs first used in the classic series. These are mostly based on greyhound racing. Personnel are usually designated a Greyhound call sign and a base of operations is known as a Trap.
  • Donna makes reference to the terrorist prisoner camps at Guantanamo Bay. This is one of the first references in the revived Doctor Who to the aftermath of the 9/11 attacks. Similarly, Martha refers to UNIT's funding being "in the name of homeworld security", a deliberate reference to the Department of Homeland Security established in the US after 9/11.
  • The cloning vat in this story is the fountain from The Fires of Pompeii, redressed. The table that is used to hold the real Martha is used in the Torchwood episode Cyberwoman. Also, the metal headwear that Martha has on at the same time looks like mind probe used the episode Sleeper.
  • This episode, and its follow-up, The Poison Sky, are the only episodes featuring Donna's family to not be written by Russell T Davies.
  • Edward Gomez provided science advice for the writing of this episode.
  • Initially, cloning was going to be a much more persistent element of the story, with the ATMOS factory workers all being clones. Russell T Davies felt that the clone idea would be more effective in small doses, however, which led to the introduction of the cloned Martha.
  • Originally, Geoff Noble was in this episode. Following Howard Attfield's death, his role was given to Wilf. The original script mentioned that Geof was unwell.
  • Originally, the story involved a new kind of chimney attached to every home which purported to cleanse the atmosphere.
  • Phil Collinson did not produce this episode. While he took time off, Susie Liggat filled in for him.
  • Luke's surname was originally Marlow, a reference to a young fan of Helen Raynor's acquaintance. This was changed to Rattigan, which had been an early name for Miss Foster in Partners In Crime.
  • The UNIT driver Ross Jenkins is a shout-out to script assistant Ross Sutherland and New Media assistant producer Richard Jenkins.
  • When interviewed on Friday Night with Jonathan Ross, Catherine Tate stated that she had been filming alongside ten actors playing Sontarans for two weeks before she realised that there were actors inside the Sontaran costumes. She had assumed the Sontarans "ran on electricity". It was not until an actor removed his helmet to reveal his real face that she realised her mistake. She stated she was "freaked out" by this and said she "nearly died".


  • 7.06 million viewers (UK final)[5]

Filming locations[]


  • Upper Boat Studios, Trefforest
  • BBC Broadcasting House, Llandaff


  • Margam Country Park, Port Talbot
  • Usk Valley Business Park, Pontypool
  • Nant Fawr Road, Cardiff
  • Orion Electric, Port Talbort
  • Roath Basin, Cardiff Docks

Production errors[]

If you'd like to talk about narrative problems with this story — like plot holes and things that seem to contradict other stories — please go to this episode's discontinuity discussion.
  • The UNIT mobile lorry is much bigger on the inside than the outside. This was explained in the next episode's commentary.
  • When the TARDIS lands where the Doctor and Martha are supposed to meet, as the camera pans, you can see that the inside panel of the TARDIS has been removed and the gap attached to the building behind it, to give the TARDIS that "bigger on the inside" look without the use of a green screen.


Home video releases[]

External links[]