I’m amazed how long Marian Keyes’s books have been lumped into that derogatory catch-all “chicklit”. I can only assume most of the commentators who do so haven’t actually read her.

Because as her legions of loyal readers know, Keyes  consistently embraces dark themes decidedly at odds with her perky covers: domestic violence, rape, rehab. They are funny, yes. They frequently contain the kind of wordplay that makes you snort with laughter at its silliness. Yet there is always a serious layer of grit beneath.

Proof copy. Nice ribbons, but they do create problems in the bath.

With her latest, The Mystery Of Mercy Close, she tackles depression, but weaves it into a mystery that is reminiscent of Kate Atkinson’s Jackson Brodie novels – and is just as unpredictable and compelling. The book’s heroine, Helen Walsh, is a private investigator – one who loves a designer handbag, can identify the paint colours of a twisted Farrow and Ball style colour chart in a subject’s home (Quiet Desperation or Local Warlord, anyone?) and who has pleasingly filthy sex with a modern-day viking called Artie. So far, so chicklit, perhaps.
But Walsh is an anti-heroine. She ‘doesn’t believe’ in hot drinks, approaches emotions with suspicion, dislikes children (a brave move in a ‘women’s’ book) and expresses herself mostly through sarcasm. She also struggles daily with depression, and her battle with it is shot through the book like Blackpool through a stick of rock.
I don’t know much about depression. I’m talking about the serious, debilitating, Black Dog kind – not the kind where you feel down in the doldrums for a bit and fight your way back up with the aid of chocolate and brisk walks. I know a bit more now.

Keyes vividly describes the relentless isolation of true depression, the dizzying, terrifying awareness that it is returning, the fear that this time the drugs won’t work, the siren call of the blackest kind of release. And mostly, the incomprehension of a world around you that can’t understand why you won’t just pull yourself together.
Walsh starts the book at a low point – her home repossessed and her career teetering (Keyes does not shy away from the financial realities of living in today’s Ireland). She accepts a job from a toxic ex-boyfriend to find a member of a boy band who has gone missing just before a lucrative comeback concert.
Walsh’s battle to find him is intertwined with the approaching juggernaut of her own depression, and her faltering belief in her fledgling relationship. If I’ve made this sound dark, it’s not semi-tonal. It zips along, with the familiar Keyes mix of endearing characters and screwball exchanges and at first the forays into depression seem almost as if they belong to another book. But gradually you realise that this is Keyes’s genius: the revelation that the severely depressed are probably around you, living apparently functioning lives, going to work daily, making hot drinks, having hot sex. And still quite able to contemplate buying a Stanley knife to top themselves the following day.

Keyes has been open about her own battle with depression. Perhaps I was so moved by this book because I believed there must be a bit of Walsh in Keyes and vice versa. I sat in bed for two hours this morning to finish it (I never do this; we are a house of lie-in Nazis) and the penultimate chapters had me weeping for its spiky, funny anti-heroine as she faced her bleakest moment. Her struggle is all the more poignant for the humour and wit that precedes it. I finished it marvelling at its originality and its honesty, and pondering how Keyes always rewards her readers in a way that many more ‘serious’ writers don’t. I concluded that the real mystery here is why she isn’t taken more seriously by the literary establishment.
I won’t say any more. But it is a brilliant, unusual, brave, sexy, book and one which I hope will confirm Keyes’s place as one of our finest writers.

Writers, I stress. Not chick-lit writers.

The Mystery of Mercy Close is out on 13th September. Do read it.