Rachel is an alcoholic commuting into London on the train each workday. At first, as her first person narration unfolds, it seems she must be about to lose her job - then after a while, it transpires that she lost it months ago and is continuing the fiction as she doesn't have the guts to tell her friend Cathy, who has been letting her have the spare room rent-free for months. Rachel's drink problem is so bad she frequently has blackouts in which she does stupid things such as making ranting phone calls to her ex-husband and his new wife or even visiting their house, which used to be hers. 
 The reader slowly discovers what an unreliable narrator she is, as all this is revealed. She takes the same train that she always did because it goes past the back gardens of the street where she used to live, after her husband bought her out. But of course she doesn't want to look at that house where he lives now with ex-mistress/new wife Anna, and their young child; it's the house a few doors along that interests her. There, the perfect couple, Jess and Jason, are often visible on their extension roof having morning coffee. Of course, the reader thinks, she knows them from when she lived at her old house. But no: she's a fantasist, making up stories about their perfect life. This couple moved in after she left the area. And then one day she sees something that shatters her illusions. Rachel is outraged by this 'betrayal' which she takes personally. Shortly afterwards, 'Jess' who is Megan in real life, goes missing, and Rachel cannot resist thrusting herself into the police investigation and the life of Megan's husband, Scott, who is under suspicion. Her attempts to unravel the truth of what has happened to Megan gives her some purpose in life, the only thing that enables her to start getting control over her drinking. 
 Meanwhile, the first person stories of Megan and Anna start to be woven into the narrative, that of Megan starting the previous year, which initially caught me out slightly. And we learn how each of these women are also unreliable in their own way with their own secrets. (view spoiler)[Megan was cheating on Scott because it gave her a sense of power - she had quite a chaotic former life as gradually becomes clear over the course of her narrative - and Anna loved being a mistress because she gloated over the thought that she was making a fool out of Rachel. (hide spoiler)] 
 None of the characters in this is what you would call 'nice' apart from Rachel's long-suffering friend who is trying to keep her off the booze and really does put up with a lot rather than evicting her. Apart from Rachel's weakness, lack of control, lying etc, and the flaws of the other two women, Scott turns out to be a control freak and partly to blame for Megan's acting out, whereas Rachel's ex, Tom, had, of course, had an affair behind his wife's back which led to the breakdown of their marriage, although his excuse is Rachel's drinking, (view spoiler)[triggered off by her inability to have children (hide spoiler)]. 
 I don't usually bother with books that have a lot of hype associated with them, so I wouldn't have read this, but a friend passed on a copy. When I scanned the first few pages, I found it quite interesting. I read some more - and then was hooked. It turns into more and more of a page turner as the story progresses though it is a fairly simple tale despite being complicated somewhat by having one of the three points of view on a different timeline. I did start to suspect the culprit as it progressed, but there was a good sense of tension in the second half, and despite Rachel initially being rather irritating, weak etc., she does improve as it goes on and I did develop some sympathy for her. All the women in this story, even Cathy in relation to her boyfriend, appear to be rather needy and reliant on men, even those who are enjoying a sense of power over them, with the exception of the woman Detective who, predictably, Rachel doesn't like, and that is a little bit monotonous. For that reason and because the three narratives are a bit 'one note' - there isn't much differentiation in the voice of the three women - I've rated this as 4-star rather than 5.