One might feel short-changed to read a book about death by Sebastian Junger that did not include some battlefield drama. After 1997’s The Perfect Storm, his bestselling account of a trawler disaster that became a blockbuster starring George Clooney, the American writer received even more acclaim for his war reporting. His narrative gifts earned him comparisons with Hemingway.

Sure enough, bullets do fly in Junger’s seventh book, a gripping exploration of the liminal space between life and death. In Afghanistan, he hid behind a meagre holly bush while “bits of leaves drifted down from bullets that were chopping through the foliage over our heads, and gouts of dust erupted around my feet”.

There’s also an account of the death, in Libya in 2011, of British photo­journalist Tim Hetherington, the colleague and friend with whom Junger had just made Restrepo, an Oscar-nominated documentary for which they spent a year at a US army outpost deep in Taliban territory.

But such passages are brief and infrequent. After decades in which he described the impact on body and mind of some of the world’s most hostile environments, it’s Junger himself for whom the bell very nearly tolls in June 2020, in the rather more comfortable setting of his Cape Cod cabin.

It started with abdominal pain but spiralled into semi-consciousness and approaching sirens as “the sky began to turn electric white”. Junger briefly rallied but his wife, Barbara, with whom he has two young daughters, demanded that he be rushed to hospital. “There was something about the way you looked at me without seeing me,” she told Junger later.

It’s in the hospital that the real drama starts. Unbeknown to the writer, he had for much of his life walked around with a “hand grenade” inside him; a rogue ligament had compressed a major artery, increasing pressure on his downstream pancreatic vessels. One of these smaller arteries had burst, causing massive internal bleeding.

A third of Junger’s slim book is therefore a terrifically detailed medical thriller, as suspenseful and pacy as an episode of peak-era ER. I could feel my own pulse quickening as the author’s threatened to stop. There are heroic doctors, bags of blood, and remarkable accounts of the medical innovations that ultimately spare him.

But it’s what happens to Junger’s mind that shakes him most. At the very point he comes closest to dying (and we’re talking seconds away) his father appears above him and slightly to his left, gently reassuring him and seeming to invite his son to join him, eight years after his own death. “He was not so much a vision as a mass of energy configured in a deeply familiar way as my father,” Junger writes.

Miguel Junger was an immigrant scientist whose rigidly rational belief system Sebastian would inherit, deepening the confusion that followed the near-death phenomenon. The rest of the book is an existential quest for understanding, as demonstrated by a vertiginous list of sources that includes studies about everything from limbic lobe dysfunction to “the near-death experience as a shamanic initiation”.

Junger has joined a blessed cohort of people who have seen death and returned to describe it. He finds remarkable patterns in other such accounts, across time, cultures and religions, and dives deep into the links between the work of the great physicists and our understanding of human consciousness (there’s also a remarkable familial link; Erwin Schrödinger, of cat fame, once had an affair with Junger’s great-aunt).

Some of the subatomic stuff is inevitably harder to digest than the hospital drama, but it remains compelling in Junger’s hands. I found his search for the nature and meaning of death – an atheist’s open-minded grappling with the unknowable – to be at once reassuring and troubling; it would be hard not to read it without wondering what flashes and visions might have greeted loved ones who didn’t make it back from the brink. This book is one reason to be relieved that Junger did.

• In My Time of Dying by Sebastian Junger is published by 4th Estate (£16.99). To support the Guardian and Observer, order your copy at guardianbookshop.com. Delivery charges may apply.