Twenty-five years ago, poet and editor Jill Bialosky’s sister Kim returned from a night out to the Cleveland home in which she lived with her mother. She rang her boyfriend, with whom she was arguing. A short while later, leaving a note on the kitchen counter, she shut herself into her mother’s Saab in the garage, turned on the ignition and consequently died of asphyxiation. She was 21. These, in Bialosky’s words, are “the bare facts”. But, inevitably and despite the great pain involved, she was compelled to search beyond them: “Where was the young child who was no different from any one of us and whose life seemed filled with possibility and hope?” she writes. “What happened to her? There had to be more to the story.”

There is, of course; as Bialosky demonstrates with unstinting empathy throughout the course of this harrowing memoir, there are worlds more to everyone’s story, although to excavate them requires immense patience and delicacy. Kim certainly had her share of unhappinesses. Bialosky’s mother was widowed suddenly when she was just 24, and had three young daughters to care for; a few years later, she remarried and gave birth to Kim, but her second husband left when the new baby was only three and didn’t see his child again for a decade. Bialosky charts the impact this early loss had on her youngest sister, recalling the most minute and poignant details, such as Kim’s tears when she lost the miniature father from her doll’s house family. In later years, Kim dropped out of school just short of finishing, took up with a boyfriend nobody liked, struggled to find a sense of purpose. But does any of this, at bottom, really explain her final act? Is such an explanation possible, and even if it is, how might one go about uncovering it?

Bialosky’s journey towards understanding is both rigorous and necessarily incomplete. She lets no possible line of inquiry go but has continually to confront the fact that Kim’s suicide, the inadequate “wall of protection” that failed to save her life, cannot be neatly summed up. Searching the literature of suicide, from Plato and Shakespeare to Charlotte Mew and Virginia Woolf, consulting an eminent professor of suicidology, painstakingly reconstructing the events leading up to her sister’s death and wondering what might have happened differently; each of these things fill more of the picture in. But, ultimately, some of it will remain obscure. “What should you do if you fear someone is suicidal?” Bialosky asks the professor. “Dare to ask,” he replies.

History of a Suicide is published by Granta (£9.99). Click here to order it for £7.99