A cold, efficient killer. A secret society. A vengeful woman.

After a frenzied attack by two drug addicts robs Maddie of her husband and youngest child, she relocates to a remote village in Scotland with her two remaining children to rebuild her life.

Her eldest son, mute since witnessing the bloody attack, becomes obsessed with a far-right politician on TV. And Maddie starts receiving mysterious emails, and she knows she has to return to London.

As her life, and everything she thought she knew about it, begins to unravel, Maddie taps into a capacity for violence she never knew she possessed.

A mother will do everything it takes to protect her children.

And avenge the one she lost.