But something about the blankness of the sand unnerved her. And the birds, she thought, where were the birds?

The moment she set foot on the Inch she felt something was wrong. She tied the three-seater RIB to a mooring post on the jetty and turned. The island looked the same, black sand shimmering in the low summer light, the sun’s rays bouncing down the Forth and hitting the island in a low-slung blaze.

Beyond the beach, hardened lava flows billowed down from the volcanic vents that dominated the island.

Scraps of moss and sea grass cut green through the black and grey of the rocky terrain, over the years they’d brought life to the newborn land and clung on.

It was too quiet, Surtsey realised, that was the problem. Where were the gulls and crows?

Scientists had been coming to the island since it emerged in a giant plume of volcanic ash 25 years ago.

The birds knew that humans meant possible food and usually greeted their arrival with a flurry of squawks and shrieks.

But she was alone, just the low ruffle of waves on the beach, the hollow thud of her rigid-hull boat bobbing against the jetty.

And where was Tom’s boat? He didn’t always moor at the jetty, sometimes he landed round the coast, paranoid about them being seen together even out here in the middle of the firth.

Hassle

But that was such a hassle and he’d been relaxed about it recently, so Surtsey was surprised not to see it tied up.

She did a slow 360, the salty bite of the sea air in her nose, and wondered what she was missing.

Inchkeith to the northwest, its lighthouse and derelict battlements silhouetted against the setting sun.

Behind it Burntisland and the three bridges, a mess of struts and cables, supports and towers.

Round to Granton and Leith harbour, the beaches of Portobello and Joppa hidden by the island’s peaks from this side.

It was deliberate that they met on the north side, in case of prying eyes with strong binoculars.

Surtsey looked up at the twin volcanic peaks, brooding in the dusk.

She had been up those slopes, explored every scrap of the Inch over many visits since she began her studies. So lucky to be a volcanologist and have this on her doorstep, the best laboratory in the world with Edinburgh University leading research.

She looked to the east, the flat expanse of East Lothian. She got a flutter of unease at the missing Cockenzie power station chimneys.

They’d been a landmark of her childhood in Joppa, and their recent demolition left a flicker of longing in her heart.

Further east was Berwick Law then open sea, tankers drifting out there, wash glittering in the light. Where was he?

She checked her phone. No new message, just the text from earlier:

“Fancy a picnic tonight? Usual time and place. Tx” “Picnic” was a stupid euphemism, Tom trying to be careful.

Unnecessary, since it was from the phone he only used for her, the phone his wife didn’t know about.

It had been going on for six months. The first time was after a drinks thing at uni, celebrating a new grant award for the research group, money that would keep everyone coming back to the Inch for years.

Flattered

After cheap Prosecco in the Grant Institute at King’s Buildings a handful of them moved on to beers at The Old Bell.

Surtsey was drunk enough to flirt with him and to be flattered by his attention.

He was 20 years older than she was and married, but he was sharp, had authority and a certain charm, still handsome and trim.

And he was ridiculously grateful, one reason she kept it going, the look in his eyes when she undressed in front of him.

He was getting to seduce a firm 25-year-old for the first time since his wife had been that age, and he was like an excitable puppy.

It was so different to being with Brendan, ages with her, cute and skinny, innocent and uncomplicated. She hit reply on her phone:

“I’m here. Where r u? x”

She walked off the jetty and jumped onto the beach. Even though she knew the geological processes that made it she was still amazed by the black sand, glistening like oil where it was wet, more like iron filings above high tide.

She lifted a handful and let it run through her fingers, then brushed her hand on her dress. She wasn’t really a summer dress kind of person.

She was usually in vest tops and jeans, but she liked to play the young ingénue with Tom, actually enjoyed the stereotype.

They both realised the cliché of the situation, older academic having an affair with young PhD student.

Surtsey imagined she was in a Richard Curtis film or a corny novel by some middle-aged Oxbridge guy.

There were no footprints in the sand. That didn’t necessarily mean anything, Tom could’ve landed round the coast and come over the ridge.

But something about the blankness of the sand unnerved her. And the birds, where were the birds?

She walked up the beach onto the patchy grass and called him. She wasn’t supposed to do that even though he kept it on silent, but something didn’t feel right.

Maybe he got caught up with Alice and the kids at home, unable to make excuses. That went with the territory, of course.

He wouldn’t have just forgotten, that wasn’t like him. One of the things Surtsey liked about their set-up was that she was at the forefront of his mind throughout the day.

Afterthought

She liked that compared to Brendan, who occasionally treated her like an afterthought.

The phone went to voicemail. She didn’t leave a message.

She walked round the coast towards the scientific hut, its white walls and blue corrugated roof stark against the black landscape.

The hut was little more than a bothy with a bed, some basic lab and storage equipment, and a stove in the corner.

He wasn’t likely to be there, they never used it, scared of leaving a trace that other department members would find.

They always chose somewhere outdoors but sheltered, on their own little island paradise only a couple of miles from Edinburgh.

That was part of this whole thing, their shared love of the Inch, the violence of its creation, its settling and erosion, the spread of life across it. An Eden for them to share.

More on Monday.