It is every writer’s dream to glimpse, peeping out from behind a news story or feature, the contours of a book. Brian Masters was eating his breakfast on 12 February 1983 when he read in the morning papers reports of the arrest of a mildly spoken Jobcentre employee accused of strangling a number of men with whose flesh he had blocked the drains in his flat in Muswell Hill. Masters wrote to Dennis Nilsen. Nilsen wrote back: ‘Dear Mr Masters, I pass the burden of my life on to your shoulders.’ After Nilsen had filled 50 prison notebooks, Masters embarked on Killing for Company, surely the grisliest yet most poignant biography of a serial killer ever written.

It was a differently horrific story that set Sophie Elmhirst to work on this superb debut, which has won advance praise from, among others, Colin Thubron, a rare puffer. During the pandemic, mid-lockdown, while researching a feature about people who chose to live on water, Elmhirst chanced on the story of Maurice and Maralyn Bailey, a British couple who, in 1973, spent 118-and-one-third days on a raft in the Pacific. The British Library and British Newspaper Archive were stuffed with reports of their shipwreck, and very quickly Elmhirst’s feature was bursting its banks to become a book.

Suddenly the air was riven with a sound like the reportfrom an ogre’s shotgun

At its heart, this is a beauty-and-the-beast love story. Maurice Bailey grew up with a stutter and a hunched back, both exacerbated by his contracting childhood TB before there was a cure. As soon as he was able, he detached himself from his family. When his mother died, he skipped the funeral. He escaped into science, burying himself in books about the origins of the universe and natural selection. But he was miserable. ‘Like all practised self-saboteurs, everything he did seemed only to confirm the abject opinion he already had of himself.’

Then he was introduced to Maralyn. She was 21, he 30. ‘Until I met Maralyn,’ he later wrote, ‘I didn’t know what affection was.’ She, meanwhile, loved it that this older man could climb mountains, fly planes and sail boats. They married, and settled down in the Derby suburb of Allestree, ‘a place where a particular kind of quiet stiffened the air and lives unfolded behind securely locked front doors’. It was the late 1960s, and Elmhirst is good at evoking an era that feels both familiar and like deep history. There were oil crises, industrial strikes and inflation.

Maurice and Maralyn itched to escape suburban life. On a wet November evening they hit on the notion of abandoning the ‘cosy oppressions of middle-class England’ to sail, via the Canaries, the Caribbean and Galapagos Islands, to New Zealand. The sale of their bungalow would enable them to buy a 31ft Bermuda sloop, not fast but solid, or ‘stiff in a blow’. They decided against a radio transmitter – Maurice wanted to sail the old way, ‘by his wits and the stars’ – and what did it matter that Maralyn couldn’t swim? They set sail in Auralyn – named for their union – on 28 June 1972.

Life on the ocean wave was tough. They had to get used to bad weather, broken sleep and relentless bouts of seasickness. They could only wash properly when they saw black clouds gather, then ‘they quickly soaped themselves and stood beneath the shower of rain, hoping it would last long enough to rinse the lather from their bodies’. But they were deeply content – ‘happy with our isolation’, Maurice wrote, ‘and at peace with everyone and the world’.

They were 250 miles north of Ecuador and 300 miles east of the Galapagos when the air was riven with a sound like the report from an ogre’s shotgun. Simultaneously, they were hit by a mighty crash, so that they felt the violence of it in their bodies. How slim were the chances that, in the whole of the Pacific, a whale should rise immediately under them? But there it was, 40ft long – 10ft longer than their boat. Mesmerised, they looked it straight in the eye before it returned to the depths, ‘a meteor landing in the ocean, showering spray’. By that time they had lost vital minutes. Near the galley and below the waterline was a hole 18in long and 12in wide, ‘the size of a briefcase’. As Auralyn sank, they grabbed food, passports, pencils, paper, flares and a biography of Richard III. Then the solid bulk of the boat was silently swallowed. They faced each other, Maurice on a dinghy, Maralyn on the raft that would become their home, which, like the Little Ease cell in the Tower of London, did not allow either of them to lie flat.

There are, Elmhirst tells us, around three million shipwrecks on the seabed. Their stories bewitch us. Recently, with a group of inmates at HMP Wandsworth, I read Michael Palin’s Erebus. The men had chosen it because they thought it would transport them thousands of miles from their cells. But it turned out to be a story of imprisonment: a ship encased in ice, sailors turning cannibal. Nothing worse, we thought.

But in some ways the story of Maurice and Maralyn is more fearful, and Elmhirst brilliantly conveys their helplessness as they bob around in their sagging bath-toy raft, miles from the nearest shipping lane. Maurice was sure they were doomed but tried not to say so. Maralyn busied herself organising their provisions as if she was back in the Allestree bungalow. They had 33 tins of food, a few dates and nuts and one Dundee cake; they rationed themselves to a pint of water each per day and very quickly became ‘obsessed by thirst’.

To begin with there might have been enough gas in the cylinder to allow them both to finish themselves off, but soon it had run too low. Whether from hunger or desperation, they began to fantasise. Maralyn was sure she could hear a plane flying overhead; Maurice was convinced there was a third person, Wayne, on the raft. They both had diarrhoea – their water supply was probably contaminated by turtle excrement – and took turns crouching over the empty biscuit tin that served as their loo. As the flesh fell off them, their faces began to ache where their skulls were pushing through taut skin. They were dying. But, as Elmhirst says: ‘You’re still alive while you’re dying.’

As the flesh fell off them, their faces began to ache where their skulls were pushing through taut skin

The irony is that, had Maurice and Maralyn been in a seaworthy, properly provisioned boat, sailing through this part of the Pacific would have been dreamy. Close to the Galapagos, Darwin’s ‘little world within itself’, they were near a convergence of five ocean currents, carrying all sorts of cold- and warm-water creatures – penguins, seals, dolphins and whale sharks. But, rather than think ‘how beautiful’, they had to ask ‘could we eat it?’, and, if so, ‘how should it be killed?’ The description of their sawing with a penknife through the leathery neck of a madly flapping turtle will be hard to forget.

By the time they are finally rescued, after several false starts and faulty flares, Elmhirst has ratcheted up suspense to fever pitch. You really do hang on to her every word. But here’s the rub. As soon as Maurice and Maralyn begin to rebuild themselves physically and psychologically, interest falls away – and there is still a third of the book to go. Reading about the massive media attention that met them when they finally hit dry land, their second boat and second long journey, and Maralyn’s death in 2002, the available material feels stretched thin across the pages.

Maurice lived on until 2017, mournful, curmudgeonly, his life without Maralyn a torture more exquisite than his four months adrift in the Pacific. Did he wish that whole nightmare had never happened, he was once asked. No – and in fact, given the chance, he might live it again. At least he’d be with Maralyn – ‘and what else is marriage, really, if not being stuck on a small raft with someone, trying to survive?’