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.

Cass's past smashes into his present when he finds a note threatening to expose his real identity. Stella and Tate must now face the prospect of another, superior, hostile life force on Carpathia and discover a way to communicate with it.

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.

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.

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.

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.

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.

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.

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 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.

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.

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.

On the Mediterranean island of Mallorca, Roper’s life of luxury and calm is shattered. Six months earlier, Burr continues her recruitment of Pine, sending him to Devon to build his cover story.

Hotel night manager Jonathan Pine receives a plea for help from a well-connected guest.

Following her capture by Marissa's men, Hanna must fight to escape from the Moroccan CIA facility and join Erik in Berlin. Along the way, she meets Sophie, a British teenager on holiday with her family, who gives Hanna her first proper taste of the real world and the thrill of adolescence. Yet despite this glimpse at normality, the threat of Marissa and her operatives is never far behind.

Erik is holding Marissa prisoner, trying to negotiate a deal to get him and Hanna safely out of Berlin. Meanwhile Hanna hides out with Dieter and his family. Desperate to know more about what her father is up to, Hanna discovers a huge secret in her own past. As an escape plan begins to form, Marissa attempts to make her own.