Tense drama series about the different challenges faced by the British Security Service as they work against the clock to safeguard the nation. The title is a popular colloquialism for spies, and the series follows the work of a group of MI5 officers based at the service's Thames House headquarters, in a highly secure suite of offices known as The Grid.
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With the Russians launching a nuclear strike on London, the only person who can help the team in this desperate hour is the traitor amongst them. With the Russians hunting them down, the team usher their traitor through London in a desperate bid to reach the codes, and the bomb, in time.
The episode was rated 8.54 from 72 votes.
The team face their toughest challenge ever: tracking down Lucas North, their Section Chief, friend and one of the best agents MI5 has ever had. Harry decides the team are too close, and brings in a specialist to help with the hunt. But it will not be easy to find a man who has nothing left to lose, and as the search becomes increasingly desperate, Harry and Lucas become embroiled in a deadly game of cat and mouse.
The episode was rated 8.51 from 79 votes.
Harry finds himself facing deportation to America following the death of CIA agent Jim Coaver. After some new evidence comes to light about the recent attacks on the United Kingdom and the Government's proposed alliance with Russia, Ruth and her former colleagues in Section D free Harry from CIA custody. Harry's suspicions see him going to another of his former Cold War adversaries.
The episode was rated 8.49 from 89 votes.
Harry is imprisoned and accused by MI5 of being the Russian mole. Lucas disappears to Moscow in a bid to gather intelligence and get to the bottom of Harry's arrest, whilst the rest of the team try to prove his innocence on the Grid. But with so much evidence against him and a traitor among the team, things aren't looking good for Harry.
The episode was rated 8.44 from 66 votes.
With India and Pakistan on the brink of war, emergency talks are set up in an exclusive London hotel. Section D faces its biggest challenge yet, as the team tries to avert the first nuclear confrontation since the Second World War. When the Indian delegation abandons the talks, it looks like Nightingale's sinister plan will succeed. Lucas and Ros place themselves in grave danger in a final attempt to defeat Nightingale, but will they make it out of the hotel alive?
The episode was rated 8.39 from 77 votes.
Relations between the CIA and MI5 are stretched after an American drone is hacked in Afghanistan whilst in British care, leading to the loss of American lives. Beecher - head of the CIA in London - arrives on the Grid to oversee installation of the US's advanced cybersecurity system, 'Cybershell', to prevent any future disasters. Lucas, out in the field, is tasked with protecting and delivering to the Grid Daniella Ortiz, the young ex-hacker turned White House cryptographer who holds the installation codes. When the Grid is hacked and locked down, the Team are plunged into a nightmare. Will they escape and prevent the theft of all CIA and MI5 intelligence? Will Lucas be able to protect Ortiz when the hackers decide to cut out the middle man?
The episode was rated 8.37 from 73 votes.
Lucas is plunged further into the depths of his past when Vaughn takes his manipulations to a new level. Ruth is approached and followed by an imbalanced council snooper who is convinced he's found a dead drop. She initially keeps her distance from him, but when her curiosity gets the better of her she ends up trapped in a situation not even he could have predicted. Lucas and Harry come face to face in the pursuit of the truth.
The episode was rated 8.35 from 75 votes.
There is new evidence of CIA agent Jim Coaver's involvement in some recent attacks on MI5. Harry ends up kidnapping his former Cold War colleague but soon ends up realising that he's been looking in the wrong place and Jim could be innocent. Harry, with Ruth's help attempt to steal Coaver's laptop from under the noses of the Americans at the US embassy.
The episode was rated 8.31 from 84 votes.
Calum is attacked by a gang of street muggers during a routine intelligence-sharing exercise with MI6. The laptop he was carrying is stolen, and contains highly-classified information on MI5's undercover assets. Their names are soon plastered all over the internet, making MI5 look incompetent and putting those top assets' lives in danger.
The episode was rated 8.28 from 83 votes.
Lucas's past comes back to haunt him when his former torturer Darshavin turns up with intelligence about a bomb in London. Harry fears Darshavin still has a psychological hold over Lucas, but Darshavin won't deal with anyone else. With innocent lives at risk Lucas must confront his demons for the sake of the nation, but can he overcome his nemesis in order to save the day or is the pressure too much to bear?
The episode was rated 8.27 from 75 votes.
The pressure is on for Section D when a secret meeting of powerful tycoons is stormed by armed terrorists and eight of the world's richest men are taken captive. But this is no normal hostage situation - undercover at the time, Ros is one the hostages. As events spiral out of control, it looks like no one will make it out alive. Is this the end of the road for Ros?
The episode was rated 8.26 from 80 votes.
The team step in when a British soldier is kidnapped by al-Qaeda. Meanwhile, an old protégé of Harry's returns to the fold after eight years in a Russian prison - but whose side is he really on?
The episode was rated 8.25 from 73 votes.
Tom Quinn has disappeared after shooting his boss Harry Pearce. He also stands accused of assassinating the Chief of Defence Staff. Chairman of the Joint Intelligence Committee Oliver Mace uses this a pretext to launch a punitive investigation of MI5. Zoe, Danny and the team must prove Tom innocent and save the service from government takeover.
The episode was rated 8.23 from 107 votes.
The country reaches crisis point when energy supplies are threatened by an explosion at a gas processing plant. With reserves on the verge of running out, Britain is forced to turn to Tazbekstan for help. But in return for energy, the Tazbek Trade and Industry Secretary, Urazov, wants carte blanche to wipe out his enemies on British soil. Is this a price worth paying or can Section D get rid of Urazov in order to secure the deal?
The episode was rated 8.22 from 74 votes.
The American president is on his way to London to chair top secret peace talks between Israel and Palestine, under the guise of his first state visit. Beth and Dimitri must keep their wits about them as undercover Home Office representatives, tasked with keeping the delegates apart until the talks. When a plot to kill the President is uncovered, they must also track down the assailant. The hotel is put in lockdown as a precaution, but are they locking the threat out? Or in?
The episode was rated 8.19 from 72 votes.
It's Fiona's birthday, and she's not going to forget it!While inspecting a possible Islamic terrorist safe house, they are kidnapped. With the threat of his son's , his wife's and Danny's life Adam must choose who won't live to see another day, Fiona or Danny? The prime minister's life is in danger, will mi5 give into the kidnappers demands - but then to everybody's surprise....Danny makes the ultimate sacrifice.
The episode was rated 8.19 from 103 votes.
With the country on the verge of bankruptcy, the Government cant pay its national debt payments. Section D are asked to get back more than a billion pounds of illegal earnings from the DeWits bank. The team have to find out what, or who, Nightingale is after Ruth's investigations into the power meeting at Basel pay off.
The episode was rated 8.18 from 77 votes.
After a Pakistani intelligence officer is murdered in south London, the head of the Pakistani intelligence service talks to Harry and Ros. They learn that there is a planned attack on some Muslims and there are determined to stop an all out war between the Hindu and Muslim communities.
The episode was rated 8.16 from 73 votes.
Harry is still missing, and there is one question on everyone's mind: is he dead, or alive? Section D discovers that Harry thwarted a clandestine operation to smuggle weapons-grade uranium into Iraq to justify the war. Now the rogue officers who masterminded the operation want their uranium back, and they are prepared to go to any lengths to get it. If Harry isn't dead already, is it too late to save him?
The episode was rated 8.16 from 81 votes.
Tom's skills as leader are tested to their extremes when they take part in an Extreme Emergency Response Initiative Exercise (EERIE) to test their response to nuclear, chemical or biological act in central London, but when the power in the grid is cut and Harry starts to feel ill, they soon begin to suspect it's for real.
The episode was rated 8.16 from 126 votes.
Last updated: nov 28, 2022
