Majella Kelly has found a subject to suit her voice – and what a voice it is, charged with images of Ireland that transport you there for better or worse, in sickness and in health, and in deepest trouble. The subject that dominates this not-to-be-missed debut is the discovery of an infant mass grave in Tuam, County Galway, the existence of which was only officially acknowledged in 2017. The wretched tale is that from 1925-1961, “fallen women” were sent to the inappropriately named Bon Secours Mother and Baby Home, run by nuns. Exactly how so many babies failed to survive is not clear but injustice, cruelty and grief surge through the poems. At the same time and strangely, even at their darkest, there is at times a fairytale quality to this writing – magic in its margins.

The title suggests a readiness for a good gossip but while Kelly is captivatingly conversational, she is preoccupied by what it means for women to be silenced. Voice is about one of the unmarried mothers gagged by shame – and Kelly’s sureness of touch is evident in the accurate rurality of “cut nettles in empty cups”, as anyone who has uprooted a nettle and witnessed its speedy wilt can confirm. The final lines of the poem are frightening in their crematorial helplessness: “But when I opened my mouth to cry out,/I spoke only in a thin grey wisp of smoke.” The plain simplicity of the nouns is exactly right (nettles, fireplace, smoke) – she does not get in the way of her subject. Elsewhere, though, there are poems that possibly over-tell the scandalous story. Clean begins: “Dead is the happiest we ever were…” The line’s authoritative flow cannot override the bitter falseness of the attestation – death being no happiness at all. And there are times when Kelly is over-reliant on lists of nouns such as strings of beads, poetic rosaries – although at their best (especially in I Am From) these have their uses.

She writes, too, about contemporary women punished for being women. The most successfully unnerving of these poems is Clipping a Cockatiel’s Wings (for Dummies), set out as two poems in parallel. The poem on the left instructs how to clip the wings of a pet bird. “Start by clipping the two outermost flight feathers./A week later, clip the next two. Continue this schedule/until the 10 primary feathers have been trimmed.” On the right side, there is a spare and more ruthless text: “She needs to know who’s boss:/it’s your house, after all. To know her whereabouts,/ensure she has no money,/get her email password,/take away her phone.” The different registers discomfitingly collide: the voice that instructs on the clipping of the pet bird has awful expertise – or expert ease. And you start to see, straying into the poem on the right, how it is a comparably unquestioning superiority that has produced the second oppressive voice.

This is a collection that seems simultaneously old and wise and possessed of a youthful and supple unpredictability (perhaps that is what middle age should aim at – Kelly is 44). We frequently find ourselves in a land of fable with familiar rhythms but uncertain outcomes. In Saint v Goddess, the pagan presses up against the modern. This is a fascinating and intricate poem about a schoolgirl giving birth in secret and about the Goddess Brigid, a silversmith, demoted by the Christians to become the saint who “invented keening”. In a beautiful, separate poem, The Art of Keening, Kelly pursues this to its inevitable conclusion as professional wailing turns into the real thing.

• The Speculations of Country People by Majella Kelly is published by Penguin (£10.99). To support the Guardian and Observer order your copy at guardianbookshop.com. Delivery charges may apply

Voice

To go into The Home was to be given
your voice on a spoon and told: swallow it.
When they shaved our heads, our voices wilted
on our tongues like cut nettles in empty cups.
When they took our names away, the tiny
venomous hairs of shame bored untold holes
in our throats. When they insisted on silence
on the birthing table, just to remind
us we had sinned, the itchy hives of guilt
distended, red and angry, in our bellies.
And when she said: the child of your sin is dead,
my heart was an extinguished fireplace.
But when I opened my mouth to cry out,
I spoke only in a thin grey wisp of smoke.