Heading south out of Kirkwall, they were soon within sight of Scapa Flow, which, as Ivan had promised, was fairly calm. Rhona noted in passing the lush green of the fields and the roadside verges bright yellow with primroses, known here as mayflowers, according to Magnus.

Despite the circumstances, Rhona was pleased to be back in Orkney.

Approaching Houton Bay, she had her first clear view of the Orlova anchored offshore. Approximately 80 metres in length, a rusted red, she resembled a supply vessel for an oil installation, with a flat cargo area at the rear. Although, according to Erling, the interior crew quarters had been substantially upgraded. If it was as luxurious as he’d suggested, there was no evidence of that on the outside. Word was that its origins were Russian and that it may have been abandoned in the Atlantic before being upgraded to become some sort of cruising ship.

As they pulled up in the ferry car park, Rhona spotted Magnus and Erling outside Magnus’s house, next to the jetty, where the police launch was tied up.

Chrissy leaped out of the car and swiftly took off towards Magnus, Rhona and Ivan following.

‘He’s another of Chrissy’s favourites,’ Rhona told Ivan with a smile. ‘She loves the Orcadian accent.’

Ivan gave a half-smile, as though thinking he was already outmatched by the tall professor Chrissy was currently embracing with gusto.

‘You’ll both stay with me,’ Magnus said after greeting Rhona warmly.

Rhona looked to Erling.

‘Makes it easier to come and go to the ship. Plus Magnus, as you know, is an excellent cook.’ He paused for a moment before saying, ‘Considering the strangeness of the crime scene, I suggest Magnus accompanies us. As a behavioural psychologist he might be able to interpret what’s been happening out there.’

That agreed, they donned life jackets and boarded the launch. Within moments they were cutting through the waters of the Flow towards the red hulk that was the Orlova.

‘How do we get aboard?’ Chrissy said.

‘By ladder,’ Erling told her. ‘Think you can manage the climb?’

‘Nothing to me,’ Chrissy said, her eye drawn upwards as the launch approached to nudge the ship’s side. ‘After Kilt Rock.’

Rhona enlightened Erling. ‘It’s a cliff face on Skye. We abseiled down.’

In fact, it did turn out to be trickier.

On Skye she’d been attached to Jamie McColl as they’d dropped down the steep cliff face. Jamie was a pal from her teenage years when she’d spent her summers with her family on the island. He was also a member of the local mountain rescue team, so the descent had demanded little effort on her behalf, except controlling her fear.

This was different. Here she would have to climb a steep ladder on her own volition, while trying not to look down at the swirling sea below.