Helen Oyeyemi’s latest novel is a story about stories; a tale that unpicks and exposes the threads that tie tales together. It’s set in Prague, with the city functioning as backdrop, cipher and, even, at times, narrator; the main characters slip, slide and transmute, and the bit-part players reappear in different roles and get-ups, like actors in a travelling theatre. Time in this city warps and winds backwards, contributing to the sense of the novel, and Prague itself, as a switchback ride: a “non-stop paternoster lift” that carries its passengers in circles rather than launching them along straight lines. The themes are love, history, identity, and – most fundamentally of all – the essential subjectivity of the act of reading; the notion that, when we open a book, we’ll each discover something different inside. Which, to be frank, makes for an interestingly high-stakes reviewing experience. This is, of course, business as usual for Oyeyemi, to whom formal experimentation and narrative instability are meat and drink. Let’s start, then, with what appear to be the facts. Parasol Against the Axe is the story of a parched summer weekend in which two women, Hero Tojosoa and Dorothea Gilmartin, converge on Prague for a hen weekend. Hero and Thea were once as thick as thieves; these days they’re not speaking, and their motives for attending the bride-to-be Sofie’s celebration are wildly different. The weekend begins prosaically enough, with a whistlestop tour of the city’s untouristy sights (“the bright-bannered hypermarkets … the ”), after which Hero is deposited at a bed and breakfast buried in the twisting streets of the old town. Alone in her room, she picks up the “Prague book” her 14-year-old son bought her for the trip: a fictional novel-within-the-novel, titled Paradoxical Undressing. The novel takes on a life of its own, gleefully jettisoning convention, and playing fast and loose with expectations It’s at this point that the concept of “facts” begins to come unstuck. The first time Hero reads Paradoxical Undressing, the opening chapter tells a whimsical tale: a young woman working in a secondhand bookshop finds scraps of paper tucked into its crumbling walls. When pieced together, they contain yet another Prague story: the adventures of a nobleman at the court of Rudolf II. Hero is engrossed, until the moment when Paradoxical Undressing appears suddenly to address itself directly to her, with an abrupt “Where are you?”. She puts the book down, disconcerted; the next time she picks it up, chapter one tells a different story entirely. Now, we’re plunged into the watchful, umbral world of Matouš Brzobohatý, a “(rightly) reviled High Court judge”, busily dispensing communist-era justice in 1957 Prague without a flicker of disquiet until the moment that he realises his son has become “a kind of sentient Party placard”. This new tale is equally absorbing – right up until Paradoxical Undressing again interrupts itself to ask Hero (and us?) “Where are you? (Do you know?)”. From here, Oyeyemi’s novel takes on a life of its own, gleefully jettisoning convention, and playing fast and loose with both its characters’, and its readers’, expectations. Hero, talking to other members of the hen party, finds she’s not the only one to have read Paradoxical Undressing; both of the brides’ mothers have read it, too, but where one remembers a “callous” story about a cold war misinformation agent, the other recalls the tale of a feud between “two of the greatest sixties pop singers in this country”, which gave her a rush “just like candy”. Meanwhile, Thea, who’s pursuing her own journey through Prague, is given a copy of the book by a woman dressed as a mole from a kids’ cartoon. When she reads it, the story it contains, which is set in the Prague of 1943, follows a young Jewish woman making a living entertaining German officers in the guise of a “taxi dancer”. These stories-within-the-story (which are all, by the way, compelling; worthy of novels in themselves) perform a range of functions, and raise a whole host of questions. On the one hand, when taken together, they do indeed create a “Prague book”, along the lines of Ivo Andrić’s astonishing novelisation of 400 years of Yugoslav history from the viewpoint of a bridge in Višegrad, The Bridge on the Drina. They collectively form a palimpsest of the city, bearing witness to the waves of history that have swept through it. On the other, they speak to the unreliability not of narrators but of narratives: the notion that novels are inconstant zones in which definitive answers, meanings and even events are hard to come by. Not only does Paradoxical Undressing show a different face to each new reader – and even, on occasion, new faces to old readers – it begins, over time, to break out of its confines: plotlines and characters escape from its pages, infiltrating, echoing and inflecting the contemporary action. And while the name of the book’s author – Merlin Mwenda – does not change, his biography appears to shift about as much as the stories themselves. Eventually, he makes a guest appearance in the flesh, as an ice-cream seller, dispensing melting cones and wisdom in equal measure. “Pick ten people, tell each of ’em the same thing … then go back and ask … what you told ’em,” says Merlin, towards the end of the book. “It’s guaranteed you’ll hear ten things you never fuckin’ said. Hardly anybody talks about what it is they’ve heard or read; we only say what we were thinking about while someone was trying to talk to us” – if Oyeyemi’s brilliant, baffling, beguiling novel has a central message, it’s this, or it was for me, at any rate. Who knows what you’ll find within its pages: the only thing I can say with confidence is that the voyage of discovery will be wild. Parasol Against the Axe by Helen Oyeyemi is published by Faber (£16.99). To support the Guardian and the Observer, buy a copy at guardianbookshop.com. Delivery charges may apply.