‘Is there really a secret poison unknown to science? It is certainly true that there are poisons which are very difficult to detect after death. Unfortunately for the convenience of murderers, however, they leave very decided symptoms at the time the victim dies, even if the poison itself leaves no trace afterwards.’

‘You’re pulling my leg,’ said Sally. ‘All the same, I still think there was something fishy about Bill’s death. He dies in the snow – and a perfectly healthy man, according to the insurance people, shouldn’t really have done that! – Tiny gets injured – nobody knows quite how or exactly when! – and the housekeeper (who might know something awkward) disappears! Then there are all these letters, and now, as you say, they have ceased. I think you ought to start throwing your weight about. It’s more than time these mysteries were all cleared up. If you sat down for a couple of hours and made your mind a blank, you’d get on to the truth in no time!’

Mrs Bradley received this involved tribute with an appreciative hoot of amusement.

‘What you want is a nice brisk walk,’ she said. Sally shuddered.

‘What a horrible idea! I took Rhu out to Topstone before breakfast and nearly walked my legs off up those hills!’ she protested. Hearing his name, the great dog got up from the hearthrug and poked his nose affectionately into Sally’s hand. ‘Nothing doing,’ she told him. The dog lay down again. The Boxer puppy burrowed against his side.

‘Well, I’d like a walk, but not with Rhu, nor even with you, Sigfried,’ said Mrs Bradley. ‘I think I’ll adopt your valuable suggestion, Sally, and make my mind a blank. It will be just as useful as continuing to allow it to run round like a white mouse on a wheel. The fact remains that we have no evidence, and suspicions without evidence are merely tiresome.’

She clothed herself for her walk, and Sally watched her out of the window as she crossed the lawn towards the rhododendrons.

‘Where’s Aunt Adela? It’s almost lunch time,’ said Deborah, an hour and a half later.

‘Hurrying uphill towards us at a pace that can’t be good for her,’ said Sally, again at the window.

‘Goodness! She must be hungry!’ said Deborah anxiously. ‘She certainly ought not to hurry uphill like that! Or else – you don’t think anything else has happened, do you?’

‘She’s positively sprinting,’ said Jonathan, watching his elderly aunt with narrowed eyes.

It was not because she was hungry that Mrs Bradley was hastening towards the house, nor even because she might be keeping lunch waiting. She had news, and the news was of such a nature that all else, even lunch, had to wait whilst she told her tale.