“He knows more about poisons than almost anybody,” I explained. “Well, my idea is, that perhaps he’s found some way of making strychnine tasteless. Or it may not have been strychnine at all, but some obscure drug no one has ever heard of, which produces much the same symptoms.”

“H’m, yes, that might be,” said John. “But look here, how could he have got at the cocoa? That wasn’t downstairs?”

“No, it wasn’t,” I admitted reluctantly.

And then, suddenly, a dreadful possibility flashed through my mind. I hoped and prayed it would not occur to John also. I glanced sideways at him. He was frowning perplexedly, and I drew a deep breath of relief, for the terrible thought that had flashed across my mind was this: that Dr. Bauerstein might have had an accomplice.