The Space Security Service or "SSS" was a military force circa 4000. (TV: The Daleks' Master Plan) Its purpose was to gather intelligence on behalf of the Solar System and when necessary, eliminate threats to that safety. They considered the Daleks paramount amongst these threats, and it wasn't uncommon for SSS agents to find themselves in battle against them.
According to one account, the SSS had its headquarters in Central City on Earth, where computers held records of the chemical makeup of every person in the Solar System. (TV: The Daleks' Master Plan) According to another, this may have been a lie. Instead, the SSS base was actually inside an unknown mountain on an unknown world, with contact through a more public location on each member world. (PROSE: The Outlaw Planet) Certainly, one publicly-known "branch location" was in Carrington City on Micawber's World. (PROSE: Placebo Effect)
The head of the SSS was Colonel Marc Forest who, with the help of the super-computer Compuvac, recruited a team made of Kurt Soren, David Carson, Sara Kingdom and Agent Seven among thousands of candidates. (PROSE: The Outlaw Planet)
Agents wore uniforms and carried blasters. (TV: Mission to the Unknown) The Service had ranks. First Rank was achieved some time after an agent joined the service and Second Rank had greater responsibility. (TV: The Daleks' Master Plan) One agent, Marc Cory, carried two documents, one giving him license to kill, the other the power to enlist any person to aid him in his mission. This included civilians. (TV: Mission to the Unknown)
Agents could not afford to have sentiment or compassion. Sara Kingdom, a Space Security agent, killed her own brother, Bret Vyon, also an agent, on orders. Though Kingdom got her orders from Mavic Chen, the Guardian of the Solar System, the Space Security considered no one above suspicion, including Chen himself. (TV: The Daleks' Master Plan) Serving the SSS was a lifelong commitment, with each agent dedicating all of their time to the defending the Solar System. For this reason, female members of the SSS were required to undergo a procedure which rendered them unable to bear children. (AUDIO: An Ordinary Life)
The Space Security Service was "newly formed" at the time of the Mars Probe 7 incident in the 20th century and was headed by General George Carrington. (PROSE: The Ambassadors of Death) It was also known as the Space Security Department or simply Space Security. (TV: The Ambassadors of Death)
According to another account, Sara joined the Service soon after her twenty-first birthday (PROSE: Top Secret) when she was chosen by Colonel Marc Forest and Compuvac as an agent in charge of the Space Security Service's field operations. (PROSE: The Outlaw Planet) To join the organisation, she had to sacrifice her capacity to have children. (AUDIO: An Ordinary life) Both of her brothers also later joined. (TV: The Daleks' Master Plan, AUDIO: The Destroyers)
For her first mission, Sara was sent to divert the plans of the Golden Dalek from Earth to Barzilla by spreading news of its gold mines amongst Dalek spies. She was successful and the Dalek forces were annihilated, an achievement for which she was praised. (PROSE: The Outlaw Planet) Early in her career, she was sent on a mission with fellow SSS agents Jason Corey, Mark Seven and her brother David, who was kidnapped by the Daleks. (AUDIO: The Destroyers)
Sara was sent to Vara to rescue the kidnapped Professor Lomberg and thus keep the secret of the formula of a new metal from the Daleks, who could use it for a new outer casing which would make them unstoppable. She sneaked into the Dalek slave camps, found the professor and helped him give the Daleks the wrong formula, causing an explosion and foiling the Daleks' plans. (COMIC: Sara Kingdom: Space Security Agent)
Charged with investigating the leak of confidential information jeopardising the security of Earth strategic bases, Sara discovered that the upgraded Golden Emperor was able to read thoughts through radio waves. She used Earth's scientists as bait whilst human forces attacked and wiped out the Emperor's fleet. (COMIC: The Brain Tappers) Mark Seven wrote a file about the mission which Mavic Chen consulted when he and Bret Vyon unexpectedly met a future version of Sara in 3999, when she was supposed to be stationed on Venus. As a result of her older self's actions, Sara received a surprise promotion and was re-assigned to Earth. (AUDIO: The Guardian of the Solar System)
In 4000 agent Marc Cory investigated a reported sighting of a Dalek ship near Kembel, though did not raise his suspicions with his superiors. On Kembel he discovered the Daleks’ formation of the Galactic Council against Earth, however was caught and exterminated before he could send word of the plot to Earth. (TV: Mission to the Unknown) Agents Bret Vyon and Kert Gantry were sent to Kembel to investigate Cory’s disappearance, however their ship was attacked and crashed landed. Injured, Kert told Bret to abandon him and was exterminated by a Dalek patrol. Bret discovered the Daleks’ plot and encountered the First Doctor and his companions. They discovered Mavic Chen’s alliance with the Daleks and worked together to escape Kembel in Chen’s spaceship, the Spar, and reach Earth. Karlton, head of the Space Security Service, was a co-conspirator with Chen and branded Bret a traitor, assigning Sara Kingdom to kill him. Sara and her backup Borkar located Bret at a research station. Sara killed Bret and pursued the Doctor and Steven Taylor, inadvertently entering a cellular transportation experiment which took them to Mira. (TV: The Daleks’ Master Plan)
By one account, the SSS had fought in the Great War against the Dalek Empire alongside the Combined Galactic Resistance. (PROSE: The Whoniverse) During the conflict with the Daleks in the 41st century, Merrick Kingdom was part of a landing party on Skaro which recovered samples of Varga plants. The samples were used in a SSS project to create guns using Varga venom. Whilst Merrick was a member, the SSS council received intelligence of an impending Dalek attack on an inhabited planet. Unable to defend it and unwilling to evacuate for fear of exposing their intelligence, the council did nothing resulting in the planet being wiped out, with Merrick's daughter Lena among the casualties. (AUDIO: The House of Kingdom)
Inspired by her aunt Sara, Lena's daughter Anya joined the SSS. (AUDIO: The House of Kingdom) In the course of her duties she became a companion of the Fourth Doctor (AUDIO: The Perfect Prisoners) and worked with Mark Seven. (AUDIO: The Dalek Protocol, Queen of the Mechonoids)
Mark Seven was charged with investigating George Sheldrake. When an SSS ship carrying him was shot down on Mira, Anya was part of the team sent to retrieve him. They encountered the Tenth Doctor and he joined their investigation, returning with them to the SSS headquarters on Earth. (AUDIO: Buying Time) There he was kidnapped and replaced by the Nun who used the SSS investigation into Sheldrake to retrieve her temporal velocitar which he'd stolen. In response to Anya and the Nun infiltrating his building Sheldrake sent Gorlans to attack the SSS, with Mark leading the defence. The SSS was caught in the middle of the temporal catastrophe caused when Sheldrake activated his time tunnels without the velocitar, which the Nun had retrieved, however the Doctor was able to use the time tunnel technology to resolve the crisis with the aid of Anya. Afterwards the SSS was unable to arrest Sheldrake due to a lack of evidence, but the Doctor believed he was ruined by the incident anyway. After the SSS’ time machine was destroyed by a Dalek, (AUDIO: The Wrong Woman) Anya and Mark chose to accompany the Doctor as he went in search of its inventor, Arborecc.
The SSS discontinued the Varga venom guns project, however its leader Doctor Abigail Crane began seeking private buyers instead which was discovered by the Tenth Doctor, Anya and Mark. (AUDIO: The House of Kingdom) On Beltros Station, the SSS ran a project to mutate grievously wounded soldiers into fake Daleks. The project was led by Major McLinn and was discovered by the Doctor, Anya and Mark. The Doctor turned the fake Daleks against McLinn and they set the base to auto-destruct to prevent anyone else suffering their fates. One of the fake Daleks, Fliss Keeley, became confused amidst the chaos and exterminated Mark Seven whilst he was trying to get through to her. (AUDIO: The Trojan Dalek)
In era that succeeded the Last Great Time War, historians who studied the Dalek race discovered an SSS archive on Micawber's World that led to them developing a theory about the Pa Jass-Gutrik. (PROSE: Dalek: The Astounding Untold History of the Greatest Enemies of the Universe)