Helen is a Black Dove, working for a private espionage company, stealing secrets from her husband and passing them on to her employers. She lives a life of domesticity with her twins Oliver and Jacqueline, but there’s much more going on in her day-to-day. When her secret lover Jason is shot dead by a long-range sniper, she’s determined to find out who killed him and why. “It’s been great fun to do all of the fighting,” said Knightley. “I’ve really enjoyed learning all of the different martial arts that I have been taught.”

When Knightley thinks of Helen, she sees an image of the comedy and tragedy mask, as Helen constantly has to perform multiple roles from one moment to the next. “Helen is whatever she needs to be, to whoever she needs to be it to,” she said. But after Jason’s death, “she can’t live with that anymore and that comes to a head in this series.”

Atonement, Pride and Prejudice, Love Actually

Sam is a hired killer, a triggerman. Lethal. Professional. Lonely. The job comes strangely naturally to him, but, on the other hand, he’s disturbed by it. “He has a conscience, which is his Achilles’ heel,” said Whishaw. He’s a man who lives on a knife-edge, but who secretly yearns for the things he can’t have. In 2014, when he met Helen, he started to find those things. 

Helen became his close friend and confidant … and then, shortly after, he met Michael — the love of his life. They settled in together, building a perfect life with a big lie at its core. Sam never told Michael what his real job was, instead claiming he worked in insurance. However, his secrets couldn’t stay secret forever, and soon his lies started to crumble, with dire consequences. Whishaw describes Sam as an assassin who’s now “returned to London to assist his friend who’s trying to avenge the murder of her secret lover, and sometimes not very successfully …”

This Is Going to Hurt, Paddington

Reed is Helen’s handler and Sam’s sometime boss. High up in the Black Doves, the enigmatic Reed is the puppet master and always several steps ahead of everyone else. Like Helen, her moral compass is skewed, and she’s ultimately looking to make the most money possible by selling secrets to the highest bidder, good or bad. 

In Lancashire’s own words, Reed “recruited Helen in good faith, and Helen has been a bit of a loose cannon.” Knightley sees Helen’s relationship with Reed as “weirdly” maternal, which makes sense as Lancashire believes Reed was likely recruited for the Black Doves at a similar age that Helen was. “Reed admires Helen,” said Lancashire. “She recognizes something of herself in her.” 

Happy Valley, Last Tango in Halifax

The Conservative minister of state for defense, Wallace entered politics as an idealist and genuinely believed he could be a force of change for good. Over the years, he’s learned that there’s more to the game of politics than pure principle, and his desire to reach the upper echelons of government caused some of those principles to slide. “Make no mistake, Wallace wants to be prime minister,” said Buchan. He’s been happily married to Helen for the last eight years, and grateful that she’s the perfect homemaker.

While Wallace may seem out of the loop about Helen’s double life and colleagues in the series, he and Whishaw go way back in real life. They met at drama school, where they both did animal study in their second year. “Some of the teachers would ask us, ‘Were you here in time for Ben Whishaw’s horse or not?’ ” said Buchan. “Sadly, I missed it, but people are probably still talking about it now.”

Industry, The Crown, Carnival Row

Lenny manages triggermen — she’s the person who gives Sam his first job. She’s as violent and dangerous as she is witty and sharp. Lenny demands loyalty from her clients and isn’t afraid to use psychological and emotional blackmail to get it. Sam soon finds himself a key member of her outfit, getting everything he thought he wanted. But the price he pays may be higher than he realizes. 

When Lenny gets wind that he’s returned to London, she reckons that he owes her. “Her relationship with Sam ended badly, there was some betrayal there,” said Hunter. “She particularly took Sam under her wing, and I always thought of it as like a son betraying her.”

Andor, The Tragedy of Macbeth

A freelance assassin who works for Lenny, Williams might seem cold and cynical, but she has an innocent heart that’s at odds with the world she’s a part of. When Hyland first read the scripts, her impression of Williams was that she takes “no prisoners and might be a bit of a psychopath.”

She and Gabrielle Creevy, who plays Williams’ partner Eleanor, built Williams and Eleanor around each other. “You could tell Joe [Barton] was starting to think of our accents as he wrote more scripts, which was really cool.”

Fifteen Love, Silent Roar

Eleanor is a dry, cynical assassin who hides her need for companionship behind a dark sense of humor. She might not want to admit it, but she’s desperate for a connection. Eleanor becomes Williams’ new partner. 

“Eleanor is very similar to Williams, they’re almost mirrors of each other and become best friends,” said Hyland. “They meet when they’re alone in the world and form this attachment.”

 In My Skin, Three Women

Michael is gentle, kind, and funny. A gay man living in London, he meets Sam in the smoking area of a pub in 2014, and the two instantly hit it off. They fall in love, and everything seems to be perfect. They plan a future together, and Michael takes the lead to figure out how to grow their family. Then one day, that all changes.

Douglas found the process of building Sam and Michael’s relationship quite intimate. “Initially, we’re portraying something very domestic and quiet, so it was interesting reading the scripts and seeing what was going on outside that: this high-octane, high-action thriller,” said Douglas.

Rye Lane, It’s a Sin

Jason met Helen by accident. They instantly fell in love and embarked on an affair. With Jason, Helen felt she could finally be a real version of herself.

After Jason is suddenly killed, Helen is forced to question what she knew to be true about their relationship. “Everybody analyzes past relationships and goes, ‘What was that about?’ ” said Knightley. “This is that, taken to the extreme.”

Warrior, Snake Eyes: G.I. Joe Origins

Hector is the youngest brother of the Newman crime family, a South London gang that started to gain prominence in 2017, when Hector was in his early teens.

The Crown

Eaves is the Conservative prime minister of the United Kingdom. “He will do anything that he can to stay in power, which probably means being less principled than he might have been,” said Akhtar.

Fool Me Once, Sweet Tooth, the Enola Holmes films

Paapa Essiedu plays Elmore Fitch, an ex–SAS soldier turned hit man. A reluctant killer, he sees no other way of using his skills so has turned to the lonely life of the triggerman.

I May Destroy You, Black Mirror