The phone on my desk shrilled, interrupting Aggie Henderson in full flow. Perhaps appropriately, she was informing me in graphic detail of the pain she experienced behind the ears when passing water. The jangling phone was a welcome relief.

I heard Jeannie's voice: 'It's the coastguard, Doctor. He says it's urgent.'

'Put him on.' After a click, I heard a familiar drawl.

'Morning, Rob, Wullie Stewart here. The place has gone mad the day in this storm. There's a tanker in trouble off Port Chalmers, Peter's taken the chopper oot to her; she's fu' o' crude an' we dinna need that in the bay. Mountain Rescue have reported some silly bugger fallen on Ranneach Mhor, and noo I've got a signal from an American yacht that's crossed the pond in this storm and all the crew are ill. They are somewhere oot in Assilag Bay. I haena' a man to spare and both lifeboats are awa' to the tanker. I managed to raise Alex Farquharson. He wasnae at home but I got him on the "Ornithologist". Onyways Alex says he thinks he can see their boat. He says if ye can get doon there he'll get ye oot to her. But ye maun hurry, the tide's coming and the causeway'll no be clear more than forty minutes or so.'

'OK, Wullie, I'll be on my way, but can you tell me anything about the sick people?'

'Och not much, their signal was gey weak. The skipper said they werena seeing properly, had very dry mouths and were vomiting. He sounded frightened; ye dinna expect that in folk that can sail across the Atlantic.'

'Thanks Wullie. Tell Alex I'm on my way and I'll meet him where he keeps the "Ornithologist".'

'OK, roger an' oot.'

I apologised briefly to Aggie, who said, 'I'll just come again same time next week.' As the old soul shuffled out I grabbed my emergency bag and, stuffing it into a rucksack, ran to the office, shouting to Jeannie, 'I'm away to Assilag. There's a transatlantic yacht in some sort of trouble. Please reschedule the surgery.'

Jeannie nodded and thrust a flask into my hand. 'I brewed some coffee as soon as I heard it was Wullie, he always spells trouble. Take it with you.'

As I turned the car out across the western road to Feadag, I wondered what on earth could cause such a sudden illness in the whole crew of a boat that had been at sea some time. Some sort of infection came to mind, but it was hard to see what could affect all of them at the same time so long after contact with other people. I began to think of the ways toxic substances could be released in a yacht. As I raced southwards towards Lutheran, it occurred to me that accidental release of carbon monoxide from an engine or a faulty cooker might be the cause.

I raced down the rough road to where Alex kept the 'Ornithologist'. There was no sign of Alex but I soon found him crouched over his radio in the boat's cabin.

'Aye, so there ye are, Doctor. I am chust trying to raise "Silver Darling" again. Yon's the yacht's name; she's from Nova Scotia.' Alex was signalling rapidly in morse. 'I made contact with her a while back. She's chust off the south point o' Assilag and sailing into the bay. But they are in big trouble. The skipper said he thocht his mate might be near deid. They can only chust manage the boat in this wind and there's chust an hour an' a hauf till the rip starts. Och, I'm chust wasting time here; they'll no answer ma call. We'll cast off and go and meet her an' see what's what.' Alex went to his engine controls. 'Cast off astern, Doctor, and we'll investigate.' The 'Ornithologist' turned into the wind and bounced fast over the waves under the thrust of her powerful outboard. As the spray lashed into my face I wondered what I might find when we reached the 'Silver Darling'.