No author likes to be pigeonholed, but Helen Fitzgerald makes it nigh on impossible with her eclectic, magpie-like collection of styles and genres. Fitzgerald is an Australian writer now based in Glasgow, and this excellent fourth novel sees her once again flitting from comedy to noir thriller and from chick-lit to violent crime in the space of a few lines of well-judged prose.

And the weird thing is, it really works. Bloody Women could never have been produced by a creative writing workshop because its author breaks most of the rules conventionally laid out in such courses. But Fitzgerald does so with such gleeful abandon and convincing authority that it’s impossible not to get swept along for the ride.

Fitzgerald has a screenwriting background and it shows – she is adept at arresting openings, tense cliffhangers and tumultuous climaxes. Bloody Women opens with our anti-heroine Cat Marsden being asked to identify the severed penis of an ex-boyfriend. When she nervously giggles at the sight of Ahmed’s member, the authorities switch from treating her as a grieving ex to considering her prime suspect. Before she knows it, Cat’s in prison for the kidnap, mutilation and murder of three ex-boyfriends.

Even worse, she’s not sure whether she carried out the crimes or not. Cat has spent the seven days before her wedding to handsome Scottish Italian Joe Rossi getting legless and sleeping with her ex-boyfriends in a serious case of the marriage jitters. With a drink problem and a lifelong battle with bipolar disorder, she has no confidence in the actual chain of events, and a sly journalist who visits her in prison to write her life story doesn’t help by turning her dubious history into scintillating tabloid fodder.

The book at this stage is a mix of Cat’s currently shambolic state of mind, the backstory of how she met her now deceased ex-boyfriends, her relationships with Rossi, her lesbian friend Anna and her possessive mother, as well as extracts from our journalist’s sensationalised version of events.

It’s all delivered at breakneck pace, although never at the expense of characterisation. Fitzgerald has the handy knack of painting a character fully with just a few short lines, and she delineates the ex-boyfriends especially well, making them more than just penis-less corpses. She also gets inside the confused head of Cat brilliantly, and really conveys the torture and turmoil of a possibly unsound mind. How would you cope if you were in prison for violent crimes, and you had no idea whether you’d actually committed them or not?

The plot takes some very leftfield swerves, turns that take Bloody Women far out of the realm of conventional crime fiction. A lesser writer would have used this excellent set-up for an entire novel, but Fitzgerald essentially ties up her main mystery a third of the way through the book, and moves on to something else. At least, she appears to, but then nothing is quite what it seems in this book.

It’s difficult to say more without giving away too many plot twists, but suffice to say the action moves far away from its origins, as Cat constantly has to reappraise who she thinks she is and who she can trust among all the mayhem.

All of which sounds very serious, and it is, but there are also regular belly laughs along the way. Fitzgerald is adept at conveying the ridiculousness of relationships, the endless little disappointments, the naive idiocy of people in the first throes of love and how that can so quickly turn to disillusion and disappointment.

And in Cat Marsden she has created a wonderfully compelling central character, one full of flaws but still somehow likeable. Cat is very real, swithering between confidence and doubt, between clarity and confusion, never knowing which way to turn to get some semblance of stability and happiness in her life.

As events spiral out of control towards a dizzying climax, Fitzgerald ramps up the pace and tension to page-turning effect, and the whole of Bloody Women proves that Fitzgerald is a writer to be reckoned with, whichever genre you feel obliged to pin on her.

Bloody Women by Helen Fitzgerald is published by Polygon, priced £8.99.