Doubt is the dominant key of Mark O’Connell’s exhilarating A Thread of Violence, a probing portrait of one of the most notorious murderers in recent Irish history.

It reads like a seance with the spirits of the still-living. Immaculately paced, A Thread of Violence generates a suspense that is formal and narratorial as much as it is a corollary of genre: we read it rapt with curiosity as to how the author will avoid the ethical pitfalls up ahead, how he can possibly pull this off without sensationalism or vulgarity. The moral murkiness of writing such a book at all is intrinsic to its architecture: there’s no getting around that, by fixing his attention on a double murderer, the prestigious writer effectively signs an endorsement on the jacket cover of Malcolm Macarthur’s life, declaring it darkly riveting, profound in its moral implications.

The unbelievability is probably most resonant. The cliche that truth is stranger than fiction hangs over this story.

That very human need to understand growls in the background of every page, drives O’Connell, fuels, alongside crass voyeurism, the true-crime boom. There’s an instinct to search for reasons. Not excuses, necessarily, but something we can all point to by way of explanation, reassuring ourselves that we’ve identified the cause of the horror.

...while O’Connell tells the story of the crimes, their background and their fallout with painstaking care, his approach is too restrained and self-searching for state-of-the-nation diagnostics or political allegory around class and power. He has produced a profound meditation on violence and its roots, on the skeining of barbarism and high culture, and on our urge to make sense of chaos and brutality.

Do any of these stories adequately account for Macarthur and his crimes? And more than 40 years after the fact, how could you tell? This unstable stratigraphy of truth and fiction is the subject of Mark O’Connell’s third book, A Thread of Violence. It is one of the most disturbing things I’ve read for a good while.

...we get O’Connell’s relentlessly self-conscious reflections on his tangled motivations for taking up the project, constantly anticipating, if not always answering, every ethical objection a reader might raise. In a sense this is a book that critiques itself as it proceeds, and, to its author’s great credit, it doesn’t always like what it finds.

Complicity hovers over these pages like a hawkmoth. Who is really controlling the narrative? Is it Macarthur: hosting O’Connell in a modest flat where the murderer’s bookshelf and a rarely watched television are sealed in black plastic? Or is it a beady-eyed journalist, probing for information and — above all — any evidence of guilt, while deploying literary strategies to shield his own engagement? A friend helpfully reminds O’Connell that Macarthur is 'a real person . . . a man who did terrible things.' Surely, after interrogating the murderer for more than a year, this intensely self-aware writer needs no friend to underline Macarthur’s monstrosity? But a mesmerised reader might welcome that jolt..

O’Connell’s new book...is at once his most classically journalistic and his most personal, as well as his most ambitious and accomplished.

A project like this leaves an author open to accusations of having their cake and eating it too, producing a critique of a form that also indulges in its conventions. But in denying us an epiphanic conclusion, and by exposing the structures (interviews, police reports, previous retellings) beneath his narrative, O’Connell tries to circumvent this problem by performing a sort of reverse citation.

Relating Macarthur’s crimes and everything written about them, obsessing over details true and imagined, O’Connell compares himself to “a prospector who had struck a rich vein of crude oil.” He is, in other words, absolutely in on the exploitation of his exercise, and our role in reading it. Alas, readers will be powerless to stop, beguiled by the book’s powerful undercurrent: a deliberation over how we spend our lives trying to make all-encompassing, narrative sense of them, all the while dogged by the limitations of both reality and our imaginations..

...an engrossing and intimate glimpse into the psyche of an actual yet improbable murderer.

Erudite, seemingly emotionless, haughty, absolutely unrepentant, and elusive, Macarthur evaded easy analysis. The resulting picture of the killer is seen as if through a proverbial dark glass—and it’s as chilling, in the end, as any Hitchcock film. A superb study of real-life crime and punishment, to say nothing of sociopathy in action..

Swirling together dogged reporting with questions about the media’s coverage of crime, O’Connell manages a gripping account that casts a skeptical eye on its own genre. Even readers put off by profiles of killers will be piqued..