The Best Episodes Written By David Farr

An environmental terrorist group is threatening to flood London if the government does not make a secret document public.

As an Algerian extremist escapes his home detention, the team fears he may be plotting a terror attack on US businesses in the UK with the help of local Iranians. However, working with the Americans to stop the attack proves a trying task given their recently-deceitful behaviour.

A live TV broadcast announcing the new peace accord between the UK, US and Iran is hijacked by armed gunmen. Can Adam and Ros defuse the situation before someone's hurt?

A teenage boy accidentally stumbles upon a government conspiracy and is instantly absorbed into the world of MI5, ending up on the run. Lucas and the team battle to protect the boy from those who wish to silence him. Harry receives a cryptic message from his asset in Russia which could be the key to bringing down the high-level MI5 mole.

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 pressure is on for Beth when she goes undercover for MI5 for the first time. She is tasked with protecting an influential oil baron, Robert Westhouse, when the team receives intel that an assassination attempt will be made on him at a meeting of top oil dealers. But an unexpected ambush throws things off course, and threatens to dredge up her murky mercenary past. Meanwhile, Lucas visits someone who never expected they would see him again.

MI5 suspect a terrorist is planning an attack from his prison cell. Guest stars Jimi Mistry.

Posted undercover at the World Trade Summit for Africa, the team discovers an assassination plot. Initially determined to put their lives on the line to prevent the murder, they are faced with a moral dilemma on discovering the motive behind the plot.

Two years later. The children go behind Susannah's back to express their desire to leave Midwich and Susannah suspects ulterior motives at work. Meanwhile, tragedy strikes one of the families. Paul and Susannah work together to uncover the truth.

After more bloodshed, the children plan to leave. Susannah volunteers to go with them and strives to get Cassie to safety. It is evident now that they must be stopped. And there's no easy way out.

Hanna and Marissa have nearly lost. Hanna is held captive by Evans while the evidence that Marissa has to bring down the program turns out to be encrypted and unusable. When Hanna tries to escape she finds what could be the key to bringing down Pioneer, but Evans’ brutal interrogation might break Hanna before she can use it.

Hanna and Marissa return to Pioneer headquarters as prisoners but with a mission to unlock the evidence they need to bring down the program. When they realize that Abbas and his daughter are in danger they race off to rescue them. In the forests outside Vienna, Hanna must save Abbas while Marissa confronts Evans one last time.

Following Gelder’s murder, Carmichael arrives in Barcelona whilst Hanna, Clara and Kat hide in a hillside villa. Hanna returns to the hotel and recovers Gelder’s target list, helped out by Marissa, who follows Carmichael to the villa and blackmails him into bringing his fellow Utrax leaders to justice. Hanna allows Clara to reunite with her mother before returning to Marissa to help destroy Utrax.

Roper and his team return to Cairo for the deal, reuniting Pine with an old enemy. Pine risks it all to put his plan in motion. A discredited Burr makes one last stand.

When Erik reveals to Hanna the truth about Utrax, she is determined to take action. Meanwhile, Marissa attempts to find out from Sawyer what has really been going on at the facility.

In a covert Romanian facility, Erik Heller evades security to rescue baby Hanna. 15 years on, father and daughter live deep in the Polish forest. Erik has trained Hanna to be an incredible killer and hunter. Yet, keen to grow beyond the boundaries of her isolated world, she begins to venture away from home. This attracts the attention of CIA agent Marissa Wiegler, who has hunted Hanna since birth.

Hanna returns to The Meadows with her cover as a loyal Utrax trainee intact thanks to John Carmichael, who leads the trainee program but has been coerced by Marissa to help. As the trainees prepare for their first missions, Marissa contacts a CIA analyst in Vienna who is on the target list, and uses him for information. While in Paris, Hanna meets her target Abbas, a charismatic young activist.

Hanna and Erik are reunited in Berlin, where they hide out with his old army friends and she learns more about her father's past. However, Hanna continues to long for the normal life she glimpsed with Sophie and becomes increasingly frustrated at the restrictions her own father imposes on her. Sensing Marissa is closing in on them, Erik and his friends begin to prepare for an attack.

Midwich is recovering from the blackout when a shocking discovery is made: every woman of child-bearing age inside the zone on May 6th has fallen pregnant. But of graver concern to Dr Susannah Zellaby is the unnerving responses of the pregnant women.

A suspicious Roper gathers his entourage around him in an attempt to root out the traitor, forcing Pine to play a dangerous game. In London, Burr and Steadman face mounting opposition from Whitehall.

Sophie and Hanna's relationship begins to turn sour over their shared interest in Anton. In the fallout from this argument, Marissa arrives at Sophie's house pretending to be Hanna's mother. Hanna finds herself torn between endangering Sophie and her family, or giving up her own freedom and going with Marissa. Meanwhile, a captured Erik is brutally interrogated by Sawyer and his men.

Realising that Hanna will no longer accept anything but the full truth, Erik takes her back to Romania so she can learn more about her past. Meanwhile, Marissa begins to sense that Sawyer has not been telling her the full truth about Utrax.

Alex unlocks a way to attack Benny Chopra and Vadim in Mumbai. He and Rebecca announce their engagement, but she starts to think he is hiding something.

Roper welcomes Pine into his inner circle, leaving Corky out in the cold. Meanwhile, Burr has concerns for the safety of her source, when she suspects key information has been leaked to the River House.

Hanna arrives in Barcelona, intent on saving Gelder and persuading Clara to leave Utrax. Hanna tells Clara the name and whereabouts of her mother, leaving her conflicted. Sandy has earnt Gelder’s daughter Kat’s trust and is furious when Clara backs out of killing them. She kills Gelder whilst Hanna and Clara escape with Kat. Marissa is tasked with finding Hanna by Mannion’s colleague, Grant.