Nash coiled himself and leaped as far as he could, landing right beside the gantry in the churning water. Surfacing with a gasp, he slithered onto the plywood, which was already beginning to float, then made his way to the split in the hull.

Inside, the passage stretched up and away like a dark tube.

‘Mia!’ he shouted, at the top of his lungs. ‘Mia!’

There was no answer.

Nash hesitated. The tube was about to become a deathtrap, full of jagged steel edges and dark corners to trap and pin him. It was as if a switch had been thrown, and abruptly the strength drained from his limbs. His feet felt glued to the platform, which wobbled from side to side.

Only self-loathing propelled him inside. And the water followed like a malevolent presence as he woodenly climbed the passageway. The light dimmed to a flickering green glow as the water pulsed and surged at his heels. The confines of the tube seemed to shrink. His chest began to constrict. All he wanted to do was escape to the light and air . . .

And then he froze.

Clinging to a door frame in abject terror, Nash was tormented by his failure. How could something that was once so easy be so desperately hard? A profound grief choked him. The old Rob Nash wouldn’t have hesitated. Where had he lost him?

Of course, he knew. He’d known all along. He’d lost him in the Octopus the day Natalie died.

In that moment of complete despair, Nash finally confronted the obvious truth he had steadfastly refused to face through all the soul-searching, the inquest, the trial by media, and the damning look in Jonathan’s eye. The awful, shameful and ugly truth that his obsession had cost him everything, because if he had just gone back at the first sign of trouble, his beautiful Natalie and their precious unborn child would still be alive today.

It was his fault.

A great racking sob erupted from the very centre of his being, echoing stark and lonely in the shrinking void of air.

‘I’m so sorry, Nat. Forgive me.’

The purging of denial left him momentarily empty, unable to think, respond or act until the super-chilled water cresting the collar of his drysuit made him gasp. The shock of it seemed to galvanise his will and free his paralysed limbs. Turning on his helmet dive lights, Nash realised he was just five metres below the closed bulkhead door. Was he going to let another woman die?

‘Mia!’ he roared, ‘Hold on!’

He climbed with a will, desperate to atone, only to be confronted by the horror of Boerman’s vengeance. Where once there was a door handle, only a raw stump of metal remained. The Afrikaner must have pounded it off with a lump hammer.

Again, Nash roared, this time in frustrated anguish. The bulkhead door was totally impossible to open from this side.