Taking place just after "Smoke and Mirrors", Tom Quinn is framed for assassinating the Chief of the Defence Staff, who was actually murdered by (believed-to-be-dead) CIA agent Herman Joyce as revenge for ruining his daughter's life. Chairman of the Joint Intelligence Committee Oliver Mace conducts an investigation into Section D, intending to fire them all as traitors in support of a senior UK political conspiracy to take direct control of MI5 and MI6. Harry Pearce recovers from Tom's shooting o
Harry activates his first sleeper agent, university professor Fred Roberts for "Operation Flytrap". Section D detonates a bomb in an abandoned council house and spreads a rumour that two terrorists died while tampering with hypothetical red mercury created by Roberts to develop nuclear weapons. Section D proceed to ruin Roberts's life by arresting him, make his family leave him and put him in debt to make any potential buyers believe he would be selling the red mercury for financial security. He
Danny Hunter is assigned to protect controversial Pakistani novelist Zuli when they are attacked by two gunmen, resulting in the wounding of bookseller Harakat. However, Adam notes that an assassin had a clear shot at Zuli but did not take it. As Zuli organises his own security, Danny befriends Harakat. Later, Section D find an aerial photograph of Mace talking with Muhammed Khordad, the head of terrorist group the Path of Light in Hebron, West Bank. Adam decides to meet the source of the image.
Influential United Nations negotiator Patricia Norton, of whom Adam is fond, is kidnapped and later found murdered. Adam discovers that a far-right pro-Israeli group called the November Committee, in which media mogul David Swift is a key member, was involved as they wanted her to cease any peace talks between Israel and the Palestinian territories. Section D finds evidence that the next target could be pro-Palestinian MP Nicholas Ashworth. Knowing that Catherine Townsend, Harry's estranged daug
Danny and Zoe are assigned to follow rogue scientist Eric Newland, an expert in plague bacteria, to a North Sea ferry, with the hopes of dissuading him from selling biological weapons to North Korean buyers. However, Government Communications Headquarters (GCHQ) learn a deal has already been made, and the two are now ordered to kill Newland by overdosing him on insulin, as he is a diabetic. Zoe is unable to perform the task as she is suffering from seasickness, so Danny reluctantly carries it ou
Zoe is put on trial for involuntary manslaughter of undercover police officer Hasan Doyan while she was undercover to stop the Turkish Mafia from transporting weapons to the UK. Zoe allegedly talked member Sevilin Ozal into killing his boss Emre Celenk, which also resulted in the murder of Doyan. Before the jury makes a decision, Zoe confides in Danny in a development that should not be disclosed to the public; Harry and Adam believed Celenk had connections with Al-Qaeda. When this was confirmed
Nine people die after taking paracetamol. Section D finds that a computer hacker breached the database of a pharmaceutical company and tainted select batches of the drug with a poison. Later, the hacker wipes out several bank accounts. Section D and the National Hi-Tech Crime Unit (NHTCU) trace the hacking to a mosque. However, when a special forces team storm it, they find nothing. The hacker strikes again, manipulating traffic lights and redirecting 999 calls to sex chat lines. Adam later real
Knighted rock star Riff and his supermodel wife B request MI5's assistance when their infant son, Alfie, is kidnapped. Mace transfers Fiona to MI5 to work undercover and befriend B. However, Adam grows concerned with her cocaine use during the operation. When the kidnappers eventually demand £3 million, Section D plants the money with tracking devices, which are disabled when the kidnappers put them under magnets in a scrapyard. Furthermore, Alfie is found dead outside the couple's house. Fiona
British Army officer turned mercenary Robert Morgan is arrested after he is found digging on a Soviet weapons cache near a Royal Air Force base, containing a missing laser designated missile. Knowing an attack is imminent in 72 hours, Danny and Adam play "good cop, bad cop" using the latter's interrogation methods to extract the information. However, Danny grows concerned with Adam's methods after learning that Adam himself was tortured in Yemen. They later find Morgan has a daughter needing a l
"Butterfly", an asset of Danny and Fiona, informs MI5 of a possible sarin gas attack against the London Underground during a speech the Prime Minister will make regarding the Iraq War. However, "Butterfly" is killed by an Iraqi terror cell led by Ahmed. On Fiona's birthday, the cell leads Danny and Fiona into a trap, revealing that the threat was a distraction to capture the two; Ahmed threatens to kill them unless the Prime Minister withdraws forces from Iraq. Adam learns of this when a female