Erling indicated he would go first, followed by Rhona then Chrissy, with Magnus bringing up the rear.

‘I’ll be there to catch you if you fall,’ Magnus assured them.

Of the actual climb, Rhona registered nothing except the image of Erling’s boots a rung or two ahead, and her delight at being helped over the railing at the top to find her feet on solid ground again.

‘Okay?’ Erling said.

‘Fine,’ Rhona assured him. ‘Glad I didn’t have to carry my gear though,’ she added, seeing it carefully stacked on the deck, having been brought up in advance of their ascent.

Chrissy appeared next, doing her best to look unfazed, although Rhona had heard her forensic assistant give voice to a few well-known Glasgow oaths on her way up.

‘Nae bother,’ Chrissy announced. ‘Right, let’s get the kit on.’

The act of donning their forensic suits changed the mood. By all accounts so far, they had now entered a crime scene, where three people had died in suspicious circumstances.

Once they were ready, Erling led them across the cargo deck, which housed three Portakabins.

‘Dorms for the crew and catering staff, we believe,’ he told them. ‘The original indoor accommodation had been significantly upgraded. There’s a helicopter pad on the bow, too badly damaged to use at present, although that looks like the original method for bringing folk aboard.’

After circling the dorms, they came across what looked like a boxing ring tucked in behind, the base a similar size, but constructed with rough wooden planks, a single thick rope serving as a barrier.

‘Some sort of fighting ring,’ Erling said. ‘The base is pretty badly stained with blood.’

Entering the main structure, he showed them the guest accommodation. ‘Four suites but possibly only one in use. We found clothes in here belonging to a male and a female.’

The king-size bed was made up. The room was tidy, as though housekeeping had been in. An open wardrobe revealed a row of clothes hanging up, both male and female.

‘The victims’ clothes?’ Rhona said.

‘We’re assuming so.’

‘Anything to identify them?’

Erling indicated there wasn’t. ‘Only the clothes and toiletries. Which is odd. But then everything about this ship is odd.’

They moved then through the staterooms, which had the same air of sudden abandonment. The long mahogany dining table had a centrepiece of two candelabras, and it looked as though two people had eaten there.

‘We found the remains of prepared food in the galley. I won’t open the door because it doesn’t smell too good.’

From there they headed down another set of stairs. This time Rhona had a sense that she was entering the bowels of the Orlova, perhaps already below the waterline.