I made the meal, eager for some mundane task to divert my mind. None of this was as I had imagined it: I had seen a man shot, a man I had never met, and in no connection whatsoever with our business. Now I had watched a man drowned, in the most ordinary of circumstances. And if we were drawing nearer to our quarry in a geographical sense, there was no sign that we were any nearer to flushing him out—or to understanding the task itself.

The drizzle continued, and as I crouched over the little stove I could see the doctor outside in the last of the daylight. He was walking the boom, plucking more birds from his mist net and depositing them in a canvas bag slung over his shoulder. They were a strange mix: small dun-coloured ground ones that had ventured offshore to the boat, seabirds such as terns and gulls and, out wide of the mainmast, a big gannet that flapped and cried in misery at its entrapment.

All of them went in the bag and I told myself firmly that this was science: a discipline that could spare no pity for a wild bird. I chopped the carrots—still firm and not yet spoiled by the sea air. As I tipped them into the boiling water there was a faint tapping on the window above me: Dr Gideon, squatting on his haunches by the glass and smiling at me. He took a bird, one of the gulls, and wiggled its head like a puppet, making faces with its beak so that I burst out laughing, though I regretted it immediately. He stuck his head around the corner into the doorway.

‘I’m no ventriloquist, am I?’ he laughed.

‘I don’t know. I couldn’t hear your voice.’

His face became serious, gentle, and he brought the rest of his body around onto the steps so he was standing in the doorway. ‘You’re sad about today.’

‘Aren’t you?’

I thought I saw doubt pass over his features, as if he were questioning himself. ‘Of course it is sad,’ he began. ‘But there are lives…always…that will end before their time, in violent ways, trivial ways. Others—you, me, the master—there is a greater purpose and we prevail. You can only persist and perhaps say a prayer for these.’

I averted my eyes by stirring at the pot, which did not require stirring. ‘Whose purpose is this greater one?’

He appeared not to hear the question. ‘There is much to discuss, I know. Would you consider taking your meal in my cabin, perhaps?’

His face was open, devoid of ill-intent or hidden purpose. The frankness of his gaze made me blush, and I cursed myself for it.

‘Doctor Gideon, I am not sure that would be proper…’