The series, starring Keira Knightley, Ben Whishaw, and Sarah Lancashire, is developed by Barton's production company Sister and Noisy Bear for Netflix.

Helen, the wife of the Secretary of State for Defence, learns that her secret identity as a spy is in danger after her lover is killed by London's underworld.

Her employers, the Black Doves, a spies-for-hire organisation – that retrieves industrial, political or diplomatic secrets for the highest bidder – send Sam, an old friend, to protect her.

[13] Writing in The Guardian, Rebecca Nicholson described the series as "gleefully pulpy" and was mildly critical of Knightley and Whishaw's portrayals, but praised cameo appearances by numerous well-known actors in supporting roles.

[14] In Digital Spy, David Opie singled out the on-screen depiction of Sam having gay sex in the first episode, stating that the series "ventures where James Bond would never dare go".