When Karen Quinn's husband Bill dies after a fall from the top of the office block where he worked, the inquest's verdict is suicide. Karen is sure it was murder, but the police can find neither evidence nor motive. Two years on she has a chance encounter with Harry Webster. Harry, a one-time member of UK Special Forces, has just sold the electronics company he founded, which specializes in covert surveillance devices. With his help she uncovers evidence that, just before his death, Bill was on the point of exposing widespread insider trading at his employer. Together they plan a risky sting that has unexpected and dangerous consequences.