From a daily commuter train, alcoholic divorcee Rachel Watson (Emily Blunt) obsessively watches the house of her ex-husband (Justin Theroux) and his new wife (Rebecca Ferguson) house. She also watches their neighbours, imagining an idyllic life between them. When one of those neighbours goes missing, Rachel is caught between helping investigate the disappearance and becoming a murder suspect herself.

It is always a girl. The Girl on the Train. The Girl with the Dragon Tattoo. The Girl with All the Gifts. Gone Girl. Girl in the Dark. Girls on Fire. There has been a relatively odious marketing trend in publishing in recent years, effectively infantilising an entire generation of fictional protagonists by transforming them from women into ‘girls’. Author Emily St. John Mandel actually did some research on the phenomenon back in late 2016. She stated: ‘ The “girl” in the title is much more likely to be a woman than an actual girl, and the author of the book is more likely to be a woman. But if a book with “girl” in the title was written by a man, the girl is significantly more likely to end up dead.’ The 2015 novel of The Girl on the Train was, as it happens, written by a woman: Paula Hawkins. It focuses ultimately on three ‘girls’, at least one of whom dies quite horribly. Whether either of the other two make it out of the story alive I will leave for viewers to discover for themselves.

There’s a deeply unusual problem at the core of The Girl on the Train, one that prevents the film from ever really taking off and making a proper impact. On the one hand it is a remarkably complicated mess of character relationships, combined with what is from the outset a visibly unreliable narrator. On the other hand, and perhaps out of fear the complex set-up will confuse the audience, it is glacially slow in places. It is, in the end, a pretty damaging combination.

That the picture is partially salvaged is down to its excellent cast and its ultimate themes. Emily Blunt delivers a tour-de-force performance as Rachel, whose alcohol addiction and wounded psychology would pose a challenge to the most experienced of actors. She portrays those flaws by acting against them: a drunkard who does not want to appear drunk; an emotional mess who desperately tries to hold things together. Her unreliability – not just around the other characters but also in how she relates to the audience – makes her one of the most fascinating protagonists in ages. In supporting roles the film feels packed with strong women: Rebecca Ferguson as new wife Anna, who manages to both form an antagonist role and remain sympathetic; Haley Bennett as the ill-fated nanny Megan; Allison Janney as a police detective investigating Megan’s murder; even Lisa Kudrow in a brief but critical role as a work colleague of Rachel’s ex-husband. On the male side both Justin Theroux and Luke Evans deliver memorable performances as two different examples of toxic masculinity.

That leads into the second strength: the film’s overall theme of how the patriarchy ruins women’s lives. A third act twist reframes much of the preceding action. While the revelation of Megan’s killer is not remotely a surprise, the full horror of their actions is rather effective and the details make everything feel rather timely. As a feminist statement it is clumsy as all hell, but it feels like a positive step – and certainly is streets ahead of the weirdly loathsome conclusion to genre stablemate Gone Girl.

The Girl on the Train is a worthwhile film, but it’s frustratingly untidy and nowhere near as good as its individual ingredients could allow it to be.