I Am Watching You (2017) by Teresa Driscoll is a psychological thriller that explores the consequences of a single moment on multiple lives. The story opens with Ella Longfield overhearing two men flirting with two 16-year-old girls on a train. After learning that the men have just been released from prison, Ella's unease grows, but she decides against reporting the men—a decision she regrets when she learns the next day that one of the girls, Anna Ballard, has disappeared. Ella finally reports herself as a witness, but that action too opens a new set of troubles for her. One year after Ella’s report, Anna is still missing and the police have few leads. A series of events spark a renewed interest in the case, and suspicion begins to loom that Anna’s kidnapper may be hiding far closer to home than anyone assumed.

Told from multiple perspectives, including Ella's, the friend's father, and the private investigator, the novel weaves a tense narrative of mystery and suspense while examining important themes such as The Unintended Consequences of Everyday Decisions, The Psychological Impact of Guilt and Inaction, and The Pervasive Threat of Violence Against Women. A Kindle bestseller, I Am Watching You features Matthew Hill, a character who makes an appearance in other books by Driscoll, such as The Friend (2018). A former journalist, Driscoll is the author of several psychological thrillers, including the bestselling Tell Me Lies (2023). Her works often discuss crime and the difficulty of bringing up children in a violent world.

This guide refers to the Thomas & Mercer, Seattle 2017 Kindle edition of the book.

Content Warning: The book and this guide contain references to child sexual abuse, pregnancy loss, self-harm, and suicide. In addition, the source text uses offensive terms for sexually active women, which are replicated only in direct quotes in this guide.

Plot Summary

Best friends from Cornwall, Anna Ballard and Sarah, both 16, are on their first solo trip to London when things go horribly wrong. Sarah and Anna fight at a nightclub, and Anna steps out and disappears. When Sarah cannot find Anna, she reports the matter to the police. The only lead in Anna's disappearance comes in the form of Ella Longfield, a Devon florist in her forties, who was on the train to London with the girls. Ella tells the police she witnessed Anna and Sarah befriend two young men, Karl and Antony, on the train, and make plans to meet them at a nightclub. Ella grew alarmed when she overheard the men tell the young women they were recently released from prison. Ella briefly thought of finding the phone number of either of the girls’ parents and alerting them. However, afraid she may be overreacting, Ella decided to wait on the call. Now, Ella is swamped with guilt at her indecision.

A year later, Anna is still missing, prime suspects Karl and Antony have fled the country, and Ella has been receiving anonymous threatening postcards, suggesting someone is stalking her. Suspecting that Anna's mother Barbara, who blames Ella for not making the call, is behind the threats, Ella contacts a private investigator to explore the matter. As PI Matthew Hill conducts an investigation, and an anniversary documentary on Anna's case is broadcast, the cold case of the disappearance regains attention. Police learn that Henry Ballard, Anna's father, was not at home the night of Anna's disappearance, as he had stated. Meanwhile, Anna and Sarah's core friend group—comprising of Anna's older sister Jenny, and Paul and Tim—row with Sarah, blaming her for letting Anna go off alone that night. A distraught Sarah overdoses on meds and must be hospitalized. Sarah has her own secrets: She suspects her father Bob might be behind the disappearance, since he was in London the night Anna vanished. Bob sexually abused Sarah when she was a child and has an unhealthy obsession with Anna.

Meanwhile, Matthew's investigation concludes that Barbara is not behind the postcards. He urges Ella to report the matter to the police. Ella often feels someone is watching her when she is alone in her shop, her stalker going as far as to try to open the door. Ella's 17-year-old son Luke decides it is unsafe for Ella to be at the shop by herself and advertises for a shop manager. Matters come to a head when Karl is traced to a town in Spain. Police spot him with a blond woman and believe it to be Anna. However, Matthew studies a picture of Karl with the woman and concludes the woman is not Anna at all. Karl is arrested, and it soon becomes clear that he and Antony have nothing to do with Anna's disappearance. Sarah reports her father to the police, but he is cleared as well. Henry has an alibi too: he was with his lover April, Tim's mother, the night Anna vanished.

The Ballards resign themselves to the fact that Anna may never be found. Barbara reaches out to Ella via Matthew to apologize for unfairly blaming Ella. At Barbara's house, Ella spots a picture of Tim and recalls that he too was on the train with Sarah and Anna. Matthew alerts the police, and Tim is traced to Devon, where he is interviewing for the store manager position with Luke. As a police team heads to the shop, Tim attacks Luke. Luke manages to knock Tim out, and the police arrest Tim. It is revealed that Tim killed Anna. Tim had been obsessed with Anna for years, photographing her and tracking her every move. The night of her murder, he met Anna outside the nightclub and convinced her to come to his flat in London, promising he'd go back for Sarah. When Anna spotted surreptitiously-taken pictures of herself in the flat, she grew wary and tried to leave. Tim choked Anna to death and kept her body in the freezer. Intrigued by Ella's connection to Anna, it was Tim who had been watching Ella as well. Since Luke had taken the same nature hike as Tim and Anna a few years ago, Tim convinced himself that Luke was interested in Anna and responded to his advertisement. As the novel ends, Luke is undergoing physical therapy for his injuries from Tim's attack, and Tim's trial is about to begin. Sarah has moved away from both of her parents and is living with her older sister Lily, working toward her A Levels. Barbara asks Ella to provide flowers for Anna's funeral, requesting an arrangement that reflects Anna's youth and her joyful nature.