The Husband’s Secret by Liane Moriarty is a modern day take on the story of Pandora and her box. It details the lives of three women who are impacted by the murder of a teen girl that happened nearly thirty years ago. The end of the novel includes an ironic twist as author Moriarty shows how tiny decisions can change the scope of dozens of lives.

Cecilia Fitzpatrick thinks that she has her life under control. Her illusion is shattered when she finds a letter written to her by her husband John-Paul. Her husband had intended for the letter to be read in the event of his death. Though Cecelia doesn't open the letter immediately, she reads it eventually. In the letter, her husband confesses to the murder of a teenager named Janie Crowley. Cecilia decides not to turn her husband in because doing so will hurt her family. This decision leaves Cecilia questioning her own moral character. She also struggles to reconcile that John-Paul is a murderer, not the upstanding man who was a good husband and father.

Meanwhile, Rachel Crowley, mother of the murder victim, deals with another blow as she learns her son and daughter-in-law will be moving to another country. They will be taking their son Jacob, who is Rachel's beloved grandson. After her daughter’s murder and the deaths of her husband and parents, Jacob has been Rachel’s reason for living.

Browsing through some videotapes one night, Rachel finds a tape of her daughter and Connor Whitby together. She believes the video is incriminating evidence that Connor was responsible for Janie’s death; however, the police don’t seem to agree. Rachel is outraged that the authorities don’t take the evidence seriously. In a split-second decision, Rachel decides to take matters into her own hands. When she sees Connor crossing the road, she hits the accelerator on her car. Instead of hitting Connor, however, she hits young Polly Fitzpatrick who has ridden her bike into the street trying to get Connor’s attention. Though Polly survives, she is seriously injured. Ironically, it was John-Paul, Polly’s father, who had admitted in the letter that he had killed Janie. Now, Janie's mother has unintentionally injured his daughter.

Cecilia tells Rachel it was John-Paul, not Connor, who was responsible for Janie’s death. John-Paul is left with the guilt of his daughter's injury. If he had confessed to the murder of Janie Crowley, Rachel would have never gone after Connor. Polly would not be facing life as an amputee.

The novel's three stories are intertwined in many ways. While timing plays a significant role in the characters' lives, it is the guilt that is carried within each that determines their ultimate fate.