The Bletchley Circle follows the journey of four ordinary women with extraordinary skills that helped to end World War II.
Set in 1952, Susan, Millie, Lucy and Jean have returned to their normal lives, modestly setting aside the part they played in producing crucial intelligence, which helped the Allies to victory and shortened the war.
When Susan discovers a hidden code behind an unsolved murder she is met by skepticism from the police. She quickly realises she can only begin to crack the murders and bring the culprit to justice with her former friends.
The Bletchley Circle paints a vivid portrait of post-war Britain in this fictional tale of unsung heroes.
When Susan Gray spots a hidden pattern in a series of murders, she tries to inform the police. But when they and her husband insist she forget her theory Susan enlists her wartime friends to try and track down the murderer.
As Susan and the other Bletchley women close in on the murderer of the five girls, a shocking discovery calls their theories into question and forces them to set a dangerous trap - a trap that puts one of them in even greater danger.
Thrown into a chilling confrontation with the murderer they have so brilliantly tracked down, Susan and the other Bletchley women become locked into a ever more dangerous game of cat and mouse that leads to a seemingly inescapable conclusion.