from Murder in the Bathhouse (1980)
The door of the cubicle in the San Francisco bathhouse swung open to reveal a naked young man, lying dead on the floor.
‘We’re baffled,’ said Sergeant O’Brien. ‘But I have detained these eight other naked men at the scene of the crime.’
Poirot’s egg-shaped head jerked forward curiously. ‘So, Hastings,’ he said, ‘what mysterious link bring nine men together in such circumstance?’
‘I suppose’, said Hastings, ‘the drought’s caused a water shortage and all these chaps have got together to share a bath.’
‘Look a little more carefully, my English friend. Do they have something in common?’
‘By golly, Poirot, they’ve all got moustaches. I think they were all members of the same bomber squadron during the war. One of the poor fellows was so badly shot up by the Hun he can’t perform his own ablutions and his old comrades have got together to give him a blanket bath.’
‘A little warmer, Hastings. But our murderer is not a man. It is a virus.’
‘A what, Poirot?’
‘A virus. The HIV.’
‘Not the high-speed locomotive, Poirot?’
‘No. I will hexplain.’
Poirot proceeded to instruct Hastings in some of the ways of the modern world.
‘Good golly, Poirot. Are you positive?’
‘I hope not, Hastings.’
‘But, but – how on earth do you know about such practices?’
‘Hastings, you forget one thing about Hercule Poirot. Since all my life I am famous for my use of the little gay cells.’