What Lies Between Us (2020) is a domestic psychological thriller novel by John Marrs. The plot involves a middle-aged woman who keeps her mother in captivity for things she may or may not have done in the past. The novel examines the power struggles and deception that can disrupt relationships, even where each party claims to have the other’s best interests at heart.

This guide is based on the 2020 Thomas & Mercer edition of the novel.

Content Warning: This guide mentions sexual abuse including pedophilia and incest, death by suicide, and miscarriage.

Plot Summary

Told from the perspective of dual protagonists, the narrative develops non-chronologically and spans 25 years. The earliest plotline concerns a family of three, including a mother, Maggie Simmonds; her husband, Alistair; and their teenage daughter, Nina, who live in Northampton, England, in the 1990s. Alistair and Nina are particularly close.

Late one night, Nina overhears Alistair expressing his love to someone other than Maggie on the phone. Afterward, Alistair visits Nina in her room and explains that he intends to leave to be with someone else. Maggie spots Alistair as he leaves Nina’s room and watches in horror as Nina, who feels betrayed, attacks him in a fit of rage, killing him. Maggie assumes that Alistair was sexually abusing Nina and is shocked to discover that Nina remembers nothing the following morning. Burying Alistair in the garden, Maggie tells Nina that he left.

Following Alistair’s death, Nina becomes increasingly promiscuous, initiating a relationship with a local musician, Jon Hunter. When Nina becomes pregnant, Maggie fakes a prescription at the doctor’s office where she works and secretly administers a drug that causes Nina to miscarry. She subsequently warns Nina that she has a rare genetic disorder that causes birth defects, a lie to motivate Nina to be more careful about having sex.

Despite Maggie’s warnings, Nina again becomes pregnant, though this time she manages to conceal her pregnancy until she goes into early labor at home. When a healthy son is born, Maggie hides the child, claiming it to be a stillborn girl. Feeling that Nina cannot be trusted with a child, Maggie keeps her drugged and gives the baby away for adoption to a wealthy family. Around the same time, Nina kills Jon’s official girlfriend with whom he lives in a jealous rage. Nina arranges the evidence to implicate Jon, who is arrested and convicted for murder; he later dies in prison. Once again, Nina has no memory of killing Jon’s girlfriend. After some research, Maggie concludes that, in moments of extreme stress, Nina enters a psychogenic fugue state, leaving her with no memory of her actions after the fact.

Over 20 years pass, with Nina and Maggie living together, each haunted by the past. Nina longs to be a mother, while Maggie is filled with guilt. When Nina looks into adoption, Maggie ruins her chances by giving the social worker a poor recommendation. Nina visits a new doctor and learns that there is no record of the medicines Maggie administered to her in the 1990s, nor any indication that she has a rare genetic disorder. She becomes suspicious and digs up the garden grave where she thought her baby was buried, only to discover Alistair’s remains. Furious at Maggie, Nina locks Maggie up in the attic, where she keeps her for over three years. Maggie insists that she acted in Nina’s best interests but stops short of revealing that Nina killed Alistair and Jon’s girlfriend.

Around the same time, Nina is approached by a young man who introduces himself as Bobby Hopkinson, who claims to be her brother. She soon realizes that he is, in fact, her son. The two become friends, though Bobby distances himself as Nina becomes increasingly possessive and bitter toward his adoptive family. After Nina confronts Bobby’s adoptive mother, he cuts off contact with Nina entirely until she threatens to harm herself. He shows up at her house unannounced and catches Nina and Maggie in middle of a fight; Maggie is upset that Nina won’t allow her to seek medical treatment for a potentially cancerous lump in her breast. When Bobby sides with Maggie, whom Nina earlier told him was dead, Nina attacks him and places him in captivity in the basement.

Ten months pass. The cancer spreads through Maggie’s body. Believing that Nina killed Bobby, Maggie sets fire to the home. After firefighters discover Maggie and Bobby’s bodies in the rubble with chains around their ankles, a despondent Nina is arrested. As the novel ends, Nina appears to be sinking deeper than ever into rage and denial.