“I call everything a story, I don’t distinguish between genres,” writes Pedro Almodóvar in his introduction to The Last Dream – ostensibly the veteran Spanish film-maker’s first collection of short stories, though, sure enough, that description doesn’t quite cover it. Assembled from a presumably dense and disparate archive of prose written between the late 1960s and the present day, the book’s dozen selections mingle elaborately fantastical fictions with candid personal essays and the odd self-reflexive curio piece that sits somewhere in between. A tight, tidy foray into literature was never to be expected from the 74-year-old, whose utterly singular cinema thrives on chaotic melodrama and billowing, sensual abandon. If The Last Dream’s unruliness comes as no surprise – it’s a mixed bag both in its form and its rewards – its occasional crystalline terseness very much does.

Almodóvar invites readers to view the book as a stand-in for the fuller memoirs he steadfastly refuses to write. That notion seems fanciful as you begin reading. The first story, The Visit, describes a transgender woman’s bloody revenge mission; others early on cover queer Catholic vampirism and a peculiar nesting-doll rewrite of Sleeping Beauty. The Last Dream takes more complete if still amorphous shape later with pieces of plain autobiography. The through line here is the restless churn of Almodóvar’s imagination and storytelling sensibility, with sexual, spiritual and cinematic fixations that we sense intrude as much on his everyday life as they do on his art.

One story, Confessions of a Sex Symbol, filters his thoughts on Andy Warhol through the perspective of an invented female character, Patty Diphusa, “a porn star in the photo-novel industry”. Another, the sparse, wistful confessional Memory of an Empty Day, resumes the subject of Warhol from the diaristic vantage point of Almodóvar himself, with scant difference between the two trains of thought. Ego collapses into alter ego and vice versa; we’re left to think that the film-maker lives with several internal monologues running at any one time. It’s when he writes directly as himself, however, that he writes best, as in the title piece – a sharp, wounded, six-page reflection on his mother’s death, where practical considerations of burial veils and family gatherings are disrupted by gnawing insecurities (did she ever like his films?) – and musings on what she might have dreamed of before she died. Such raw, conversational simplicity feels bracing, the book serving as an outlet for something Almodóvar can’t express from behind a camera.

The fictional pieces, on the other hand, largely read as early treatments for films he either has made or never got around to shooting, which isn’t always to their advantage. The aforementioned The Visit is plainly a crude, even naive blueprint for Bad Education, the director’s searing, shapeshifting 2004 study of Catholic school abuse and trauma, which was itself richly coloured by personal experience – but the story has none of the film’s narrative or emotional intricacy. It also boasts the collection’s clunkiest prose, though perhaps the translation is to blame for a sentence where the narrator professes himself “stunned” by “stunning cocktail dresses”. Too Many Gender Swaps is rather more intriguing for the director’s cultists: a witty reflection on artistic collaboration and homage (a short hop from plagiarism, the narrator drily notes) in which one can see the roots of both his glorious 1999 Tennessee Williams riff All About My Mother and his melancholic 2019 autofiction Pain and Glory.

But we’re left to wish for the film he might have made of The Mirror Ceremony, a silly, sardonic, rather wicked doodle on the consequences of a jaded Count Dracula joining an austere Italian monastery. Strangely, Almodóvar has never made an outright horror film, and it’s easy to sense what this one would have looked and sounded like – though reading such ideas on the page rather shows up the absence of sensory detailing (his signature saturated primary colour-blocking, for one, or his florid use of music) that they’d have on the screen. The Last Dream has its pleasures – some of them lurid, some rather poignant – though at no point does it suggest an artist who has hitherto missed his calling.

• The Last Dream by Pedro Almodóvar, translated by Frank Wynne, is published by Harvill Secker (£16.99). To support the Guardian and Observer order your copy at guardianbookshop.com. Delivery charges may apply