Spooks is a series well-known for its shocking twists and turns, as well as frequently killing off main characters, sometimes as early as a series premiere. Unmarked spoilers below!
Series 1:
- "Looking After Our Own": Tom and Helen's plan to infiltrate a right-wing leader's gang ends horribly. The leader, Robert Osbourne, kidnaps Tom and Helen and proceeds to interrogate the latter. After Osbourne brutally burns Helen's hand and face in a deep fryer, he immediately kills her.
- "Lesser of Two Evils": The leader of an Irish splinter group sets of a Time Bomb on a laptop in order to disable MI5. Problem is, the laptop the bomb is on is the same laptop that Tom acquired and left inside his house, with Ellie and Maisie locked inside and Tom unable to help either of them.
Series 2:
- "I Spy Apocalypse": VX nerve gas is deployed in the city, and MI5 is put on lockdown. As the group becomes more and more unhinged, Tom finds out that some of the gas leaked into the Grid, and Harry is infected. Two Home Office executives try to leave the building, and Tom is forced to shoot them. Moments later, we find out that the entire situation was a drill; London is perfectly fine, and Harry was never infected. Also Tom breaks up with Vicky.
- "Smoke and Mirrors": Tom is framed for the assassination of the Chief of the Defence Staff. Although Tom tries to desperately convince Harry, Danny and Zoe that he was framed, they don't believe him. Seeing no other option, Tom shoots Harry and flees, and then swims out into the sea.
Series 3:
- "Persephone": Zoe is put on trial due to suspicions of manipulating an arms dealer into killing his boss, which also led to the death of a police officer. However, halfway into the episode, it's revealed that she did tell him to kill his boss, but didn't expect the officer to be killed as well. Zoe is found guilty and is sentenced to prison. As she awaits transfer, Harry and Danny meet up with her and let her know that Harry has arranged for her to flee to Chile with a new identity. Eventually she agrees and leaves the country.
- "The Suffering of Strangers": Fiona and Danny are kidnapped by a group of terrorists. They manage to break free, but are soon recaptured, and Danny kills one of the terrorists in the process. When the leader of the terrorists calls Adam and tries to force him to choose between killing Danny or Fiona, Danny provokes him, and is executed as a result.
Series 4:
- "Syria": Fiona ex-husband, who was allegedly hanged for his crimes, resurfaces. After she fails to rescue the Syrian Foreign Minister from death, her ex-husband kidnaps her and plans to flee the country with her. Fiona manages to escape just as Adam finds her, but before she's rescued, her ex-husband shoots her in the back. She dies in Adam's arms moments later.
Series 5:
- "Gas and Oil": Several businessmen conspire to take over Britain by throwing London into chaos. After a few parliament members are killed and a gas and oil depot is attacked, they also attempt to cause a mid-air collision over London. As the city begins to protest, they order the police to arrest and even shoot some of the protesters, nearly turning London into a war zone. Ros, the conspiracy leader's daughter, aids MI5 and helps put an end to their schemes. In the aftermath, some civilians have been killed, Juliet is paralyzed from the waist-down due to a car bomb, and Colin is hanged by the conspirators.
Series 6:
- "The Virus (Part 1)": MI5 detonates a bomb on a train in order to kill an Iranian agent who plans on attacking London. Not only are innocents killed in the blast, but the agent escapes, and is later revealed to be infected with a virus. When Zaf tries to escort him to safety, he's shot and wounded by mercenaries, and the agent becomes symptomatic; they later release the agent into the public in order to infect London.
- "The School": After spending the whole series looking for Zaf, MI5 discovers that he was tortured to death by a group of mercenaries called the Redbacks. The Redbacks return to London and kidnap Jo, and later Adam. As the two wait to be rescued or tortured, Jo begs Adam to kill her so she won't have to suffer or be coerced into giving up intelligence. The series ends with Adam cradling Jo's body, implying he went through with killing her.
Series 7:
- "New Allegiances": MI5 discovers a terrorist intends on car bombing a memorial service. After the terrorist kills herself, Adam gets into the car and drives it to an unpopulated zone. The moment he sets foot out the car, the bomb goes off, with Adam still in the blast radius. The episode ends with the team mourning his death, and Harry telling Wes that his father's been killed.
- "The Mole": Harry is arrested and interrogated after being framed as the FSB mole in MI5. Lucas heads to Moscow to meet with a Sugarhorse asset, Maria Korachevsky, only for her to be murdered mere moments after she assists him with finding the true FSB mole. Ben later finds out from Lucas that the traitor is Connie, and she slashes his throat to keep him from exposing her secret. Shortly after Harry is released and Connie is arrested, Harry and Ros find out that the Russians are planning something dire in the near future.
- "Nuclear Strike": Section D learns that Tiresias, Russia's own version of Sugarhorse, intends on setting off a suitcase nuke in Grosvenor Square. As the team try to find the bomb, they're attacked by a Russian hit squad. Harry, seeing no alternative, offers himself to the Russians if they call off the attack—which they do. Section D acquires the bomb, but there's no time to defuse it properly; Connie dismantles it so it's no longer nuclear, but dies when the bomb explodes anyway. Just as Lucas calls Harry to inform him of the situation, it's revealed that Harry's been taken hostage by the Russians.
Series 8:
- "Episode 8": Nightingale tries to start a war between India and Pakistan by bombing a peace negotiation at a hotel and killing the Pakistani President, as well as the Home Secretary. Ros and Lucas manages to stop the Nightingale operative who set the bomb, but realize they can't defuse it. Seeing no other option, Lucas hauls the paralyzed Pakistani President out of the hotel, while Ros stays behind and struggles to evacuate the Home Secretary. Ros doesn't make it out in time and the bomb explodes, killing her and the Home Secretary.
Series 9:
- "Episode 7": Vaughn, threatened by the Chinese, kidnaps Maya and forces Lucas to get the Albany file or else he'll hand Maya over to them. Section D continues their investigation of Lucas and eventually apprehend him. He comes clean about his past; his real name is John Bateman, he inadvertently set off a bomb in a British Embassy that killed seventeen people, and he took the identity of the real Lucas North. After coming clean, Lucas confronts Vaughn, only for Vaughn to expose that Lucas knowingly planted the bomb in the Embassy; Vaughn dies shortly afterwards after Lucas stabbed him earlier. With nothing left, Lucas goes rogue, claiming that "Lucas North is dead."
- "Episode 8": Lucas kidnaps Ruth and offers Harry a deal: he'll let Ruth go in exchange for the Albany device. Harry, begrudgingly, gives Lucas Albany, and Lucas later gives up Ruth's location. Maya confesses he knows everything about Lucas and that she has a tracker planted on her; Lucas tries to drive away with Maya, but she's accidentally shot and killed when Dimitri, Beth, and Alec open fire on his vehicle. With nothing left to lose, Lucas forces Harry to meet him alone on a tower or else he'll set off a bomb. Harry confronts Lucas and tries to get through to Lucas by asking him who he is. Lucas, distraught over everything and Maya's death, throws himself off the tower to his death.
