‘It’s the minefield,’ Harry replied. ‘The full extent of it has only just come to light. Twelve mines were laid by German U-boat 75. The Burdigala caught the first mine, the Britannic caught the second, but if she hadn’t, she almost certainly would have caught one on her return. The ship would be lower in the water, transporting four thousand casualties, many of whom had lost limbs and wouldn’t have stood a chance. Add to them, over a thousand medical staff and crew. Can you imagine the carnage if she’d gone down under those circumstances?’

As the information filtered through, Shelly realised her great-grandmother had been vindicated after a lifetime of self-blame. She didn’t understand why, but Shelly also felt she had in some way been released from a great weight too.

She had always blamed herself for not being able to rescue David when he needed her. Now, it was as if she had woken from a nightmare and saw the reality of the day.

If Shelly had been able to dive, and she had gone down to try and release David, she would almost certainly have become entangled too. She would have drowned and never known the tiny egg that was dividing and multiplying in the dark miracle of her womb. DJ would never have come into existence. She felt a tear slide down her cheek and, unnoticed, stepped outside for a breath of fresh air.

*

‘What’s happening on the other two screens?’ Shelly asked. ‘It looks like a tight spiral staircase. Is that another drone filming?’

‘It’s drone 2,’ the operator answered.

‘My grandmother talked about a spiral staircase behind her cabin on F deck. She said the boilermen made a huge racket in their hobnailed boots, changing shift.’

‘Ah, no. This staircase is going up inside the mast to the crow’s nest. We’re looking for the ship’s bell. It would be easier if the Britannic had settled on an even keel, then the bell would probably be at the bottom of that staircase. Unfortunately, she’s on her side, so it could be anywhere. Look, the spiral’s blocked with debris where the mast’s bent. It may be in there, but he’s giving up and going back out.’

‘I guess it would be the icing if they found it?’

‘Certainly would. The bell is the ultimate treasure.’

The drone came back into the open and took a 180 degree shot. The video diver appeared to glow in a great pool of light, like a giant radio-active spider. Attached to his body were six long, jointed legs, each carrying a powerful spotlight on the end. He was filming two divers collecting samples of marine crustaceans for analysis. The drone returned to the mast and travelled up its outside, then on an angle at the crow’s nest where the mast had almost snapped in two.