Helen Webb is a quick-witted, down-to-earth, dedicated wife and mother who also happens to be a professional spy. For the past decade, she has been passing on her politician husband's secrets to the shadowy organization she works for, known as the Black Doves.

When her secret lover Jason is assassinated, her spymaster Reed calls in Helen's old friend Sam to keep her safe. Together, Helen and Sam embark on a mission to investigate who killed Jason, leading them to uncover a vast, interconnected conspiracy linking the murky London underworld to a looming geopolitical crisis.