On an uneventful day after work, Ella Longfield boards a train back home from work in London. Lost in her thoughts, she is obsessing over her decision to buy a trashy magazine in order to appear more "with it" to younger people - a typical bad decision in the day of a woman barrelling towards a midlife crisis. She is a mother, has a loving husband, and is engaging in a mental duel with herself about decisions she wishes she had made differently. Two young men, ostensibly of questionable backgrounds, board the same train, and proceed to flirt with two young women who are on their first visit to big bad London. The flirtation leads to the twosome making plans to show the girls around, and Ella's maternal instincts prompt her to protect the young women, another decision she grapples with before choosing to stay silent.

A day later, Ella learns of the disappearance of one of the girls she saw on the train - beautiful Anna Ballard. Cut to one year down the line, and Anna still hasn't been found. Ella is not just consumed by guilt over her inaction and refusal to follow her gut instinct on that fateful night, but also has been receiving threatening letters that are driving her to desperation. Added to the letters, new evidence comes to light that the other girl with Anna on the train, Sarah, may not have told the entire truth about what really transpired the night Anna disappeared. Is there more to Anna's disappearance than meets the eye? And why is someone targeting Ella? Who is this mysterious letter writer? How are all of these characters connected? Read Teresa Driscoll's I am Watching You to find out.

Driscoll, a former journalist and BBC TV presenter, has covered her fair share of crime during her journalist years, and is said to draw upon her experiences while on the crime beat to inform the characters and plots of her mystery novels.

As a narrative writer, she pays close attention to characters, and each one feels fleshed out in this novel, a feat that is difficult when writing about a ragtag bunch of characters with more dissimilarities than you can count on your fingers. You can tell that Driscoll reaches into a fount of empathy she has obviously felt towards the families she must have encountered while covering crime for over 25 years.

From the lead character Ella Longfield, whose narrative is recounted in the first person, to Anna's parents, who are themselves battling marital issues, to Sarah and her parents, to Matthew the private investigator looking into the letters that Ella's been receiving, and a horde of secondary and peripheral characters that make up this London mystery, not one of them feels like they don't belong in the story.

Driscoll's greatest achievement has to be that she makes her readers genuinely care and feel invested in each of these characters, their individual quirks, their backstories, life's little details that haunt each of them, their foibles, and flimsy attempts to stay together. And she makes the reader feel like they can relate on some level to every single one of them.

You will remember not just their stories and their connect to this mystery, but also their names, something you don't really expect from a novel that is home to so many characters in a little under 300 pages. The narrative itself flits between first-person and third-person accounts, where some of these characters become the custodians of their link to the story.

To help things along, Driscoll calls to attention who the narrator is at the beginning of each chapter: the witness, the father, the private investigator, the friend, and the ominously italicised 'Watching' to distinguish the letter-sender from the rest of the bunch. Sentences and paragraphs and indeed chapters, are rendered in a staccato move-the-plot-breezily-along fashion, so pacing also gets a big yes.

Where Driscoll falls short is the biggest disappointment of all: plot. The whole joy of reading a mystery novel for someone who loves mystery novels is to be able to pick up on the clues the writer peppers her narrative with. Speak to any mystery buff you know, and they will tell you they knew who the murderer/killer/culprit was somewhere halfway into the novel.

The mystery reader always picks up on clues, and solves the mystery, and that is the most fun part. In her bid to construct a patchwork quilted narrative, Driscoll makes the cardinal sin of not being able to tie it together, and the ending comes so very out of left field that the reader is left with a zombie-like feeling of what-in-the-world-just-happened. Perhaps stringing together this interlaced narrative demanded so much in terms of characterisation that the plot had to inevitably suffer. Or perhaps Driscoll was so invested in her characters that she was confused as to whom to pin the tail on towards the end.

Worth a read for the characters, but not so much if you like a good mystery.