‘Because none of us would!’ Archer cried, in a voice loud enough to attract attention from those seated at the tables around them and cause a brief lull in the genteel murmur of conversation and chink of cutlery. ‘Surely you must be mistaken. What does Mr Holmes say?’
Harry hesitated, avoiding Oliver’s gaze. ‘He is attempting to identify the poison,’ she said, after a moment. ‘But he also feels that the safest course of action is to remove Mr St John from Thrumwell Manor. To put him beyond the reach of the immediate danger.’
Archer shook his head, unwilling to accept her words. ‘It cannot be. None of them would harm him – aside from anything else, their livelihoods depend on him.’
‘And yet it appears one of themisharming him,’ Harry said, with quiet determination. ‘If he were being inadvertently affected by something in your household environment – lead pipes, for example – then you would all be unwell with the same symptoms. But it is only your uncle who suffers, and itseems to me that his symptoms could logically be explained by something more than a sudden psychological affliction.’ She met his tormented gaze with much sympathy and fell back on the principles of Sherlock Holmes. ‘If we rule out all other possibilities, then what remains, however improbable, must be the truth.’
He was silent for a long moment, then turned brooding eyes upon Oliver. ‘Do you agree?’
‘I trust what Miss Moss tells me,’ he said simply. ‘Given all she has described, I think it possible, perhaps even probable, that her suggestion fits, although I don’t think we have all the pieces yet.’
‘Then we must find them,’ Archer rumbled. ‘If it is poison then we must establish which of the household is responsible for such a monstrous act and we must confront them.’
Harry exchanged a look with Oliver. ‘There may be more than one involved,’ she warned. ‘It might be a partnership, or perhaps even all.’
Archer’s brows furrowed in consternation. ‘I cannot believe that,’ he exclaimed, once again garnering curious looks from their fellow diners. ‘Agnes is devoted to my uncle – Mary too. And Donaldson has helped me carry him from the fens when it would surely have been easier to let him perish if he meant him ill.’
‘And yet someone is responsible,’ Harry pointed out as gently as she could.
‘But not all,’ Archer held. ‘I cannot believe they are all three bent on harm. However, I agree we must resolve this matter soon, before it is too late.’ He looked from Harry to Oliver. ‘Will you come this weekend? Commit to catching whoever is responsible before my uncle succumbs to their wickedness?’
His anguish was so palpable that Harry could not refuse him, even though she was not at all sure she could bring matters to a head so quickly. ‘Of course,’ she said. ‘I will come.’
‘As will I,’ Oliver said. ‘But if we cannot establish who is to blame, perhaps you should consider taking Mr St John away.’
‘As you wish,’ Archer said, and checked his pocket watch. ‘I should certainly hurry back to Cambridgeshire. My head is still spinning from all you have said but it may be that my presence will protect my uncle, although I admit it has not helped much so far.’
His words prompted Harry to make another suggestion. ‘Try to act normally if you can,’ she said. ‘If the poisoner thinks they are discovered, they might be tempted to take more risks, which could put you and your uncle in terrible danger.’
Archer’s smile was bleak. ‘Acting is perhaps the only thing I can manage, Miss Moss.’
After he had gone, Oliver fixed Harry with a curious stare. ‘You said Holmes was trying to identify the poison used. Does that mean you have been looking into the possibilities?’
She nodded. ‘With the aid of a book I borrowed from the library.Mortlake’s Common and Uncommon Poisons.’
He raised an eyebrow. ‘I see. And has Mortlake been of much help?’
‘He has,’ she said. ‘If nothing else, I’m now well-versed in all the ways one human being might poison another. It seems a lot of these substances are far too easy to get hold of.’
‘Believe me, I know,’ Oliver said. ‘Cases of poison are all too common in court, in spite of the authorities’ efforts to make them harder to obtain.’
‘Whatever it is, it’s not one of the usual suspects,’ Harry said. ‘We can rule out arsenic, strychnine, hemlock and a whole host of other Agatha Christie favourites. The symptoms don’t fit.’
Oliver drank the remainder of his tea and dabbed at his mouth with a napkin. ‘You’d better get back to your research, then. What time shall I pick you up tomorrow? Five o’clock?’
Harry bit her lip, wondering whether to tell him she planned a trip to Brighton before they could leave for Thrumwell Manor. ‘Better make it six,’ she said, deciding to keep the day trip to herself for now. ‘I’ve got a few things to take care of first.’
He shook his head. ‘I can’t believe you’ve roped me into another of your Holmesian escapades.’
Harry smiled. ‘Oh, admit it, Oliver. You’re enjoying yourself.’
He sighed as he signalled for the waiter. ‘That’s half the trouble. I rather think I am.’
Mr Babbage took Harry’s request for a day’s holiday well, even though it was, as she pointed out, terribly last minute. ‘Sometimes we just have to seize the moment, Miss White,’ he said jovially down the telephone. ‘A trip to the seaside sounds like a capital idea. It’s not as though you have anything urgent awaiting your attention here, is it?’
‘No,’ Harry agreed. ‘Mr Holmes is hardly going to investigate any of the letters he receives behind my back, is he?’
Her employer chuckled and she could picture his jowls wobbling with amusement. ‘Exactly so,’ he said. ‘I’ll trust you to fill in the relevant paperwork on Monday when you’re back. Have a nice time.’