The Bodley Head, a distinguished British publishing house, signed contracts with only two women authors in the 1920s: Agatha Christie and Annie Haynes. Christie soon moved to another house (with more lucrative terms) but Haynes stayed and her 10 very popular golden age crime novels were published prior to her death in 1929. Many of her books, including The Witness on the Roof, take place during the late Victorian period.

Running away from her abusive stepmother, a little girl scrambles across London rooftops, a favorite hiding place. She peers through a window and sees a man apparently burglarizing a studio, but quickly realizes that she has witnessed the aftermath of a murder when the man puts a gun in the hand of a body on the floor. When she cries out he glimpses her and she escapes in terror. Very soon after, she is sent to live with her deceased mother's aristocratic family and her secret is kept from the police.

A decade later Joan Davenant has become the wife of the dashing Lord Warchester and the incident from her hardscrabble childhood that once terrified her seems unreal, like a bad dream. Then one day both worlds collide when she unexpectedly locks eyes with the man she had glanced through the window. Haunted by this new knowledge that could change her life forever, a heartbroken Joan finds herself compelled to seek out the truth.