‘Well, now,’ Dr Curtis said. ‘It’s quite a little problem, you know. I can’t see a verdict of accident, Alleyn, unless the coroner accepts the idea of her presenting this spray gun thing at her own face and pumping away like mad at it to see how it works. The face is pretty well covered with the stuff. It’s in the nostrils and mouth and all over the chest and dress.’

‘Suicide?’

‘I don’t see it. Have to be an uncommon determined effort. Any motive?’

‘Not so far unless you count a suspected bout of tantrums, but I don’t yet know about that. I don’t see it, either. Which leaves us with homicide. See here, Curtis. Suppose I picked up that tin of Slaypest, pointed it at you and fell to work on the spray gun – what’d you do?’

‘Dodge.’

‘And if I chased you up?’

‘Either collar you low or knock it out of your hands or bolt, yelling blue murder.’

‘Exactly. But wouldn’t the immediate reaction, particularly in a woman, be to throw up her arms and hide her face?’

‘I think it might, certainly. Yes.’

‘Yes,’ said Fox glancing up from his notes.

‘It wasn’t hers. There’s next to nothing on the hands and arms. And look,’ Alleyn went on, ‘at the actual character of the spray. Some of it’s fine, as if delivered from a distance. Some, on the contrary, is so coarse that it’s run down in streaks. Where’s the answer to that one?’

‘I don’t know,’ said Dr Curtis.

‘How long would it take to kill her?’

‘Depends on the strength. This stuff is highly concentrated. Hexa-ethyl-tetra-phosphate of which the deadly ingredient is TEPP: tetra-ethyl-pyro-phosphate. Broken down, I’d say, with some vehicle to reduce the viscosity. The nozzle’s a very fine job: designed for indoor use. In my opinion the stuff shouldn’t be let loose on the market. If she got some in the mouth, and it’s evident she did, it might only be a matter of minutes. Some recorded cases mention nausea and convulsions. In others, the subject had dropped down insensible and died a few seconds later.’

Fox said: ‘When the woman – Florence – found her, she was on the floor in what Florence describes as a sort of fit.’

‘I’ll see Florence next,’ Alleyn said.

‘And when Dr Harkness and Mr Templeton arrived she was dead,’ Fox concluded.

‘Where is Harkness?’ Dr Curtis demanded. ‘He’s pretty damn’ casual, isn’t he? He ought to have shown up at once.’

‘He was flat out with a hangover among the exotics in the conservatory,’ Alleyn said. ‘I stirred him up to look at Mr Richard Dakers, who was in a great tizzy before he knew there was anything to have a tizzy about. When I talked to him he fainted.’

‘What a mob!’ Curtis commented in disgust.