I was quite affected by this token of Poirot's regard.
"So I accepted," he continued, "and in an hour's time I must leave to catch the boat train. One of life's little ironies, is it not? But I will admit to you, Hastings, that had not the money offered been so big, I might have hesitated, for just lately I have begun a little investigation of my own. Tell me, what is commonly meant by the phrase, 'The Big Four'?"
"I suppose it had its origin at the Versailles Conference, and then there's the famous 'Big Four' in the film world, and the term is used by hosts of smaller fry."
"I see," said Poirot thoughtfully. "I have come across the phrase, you understand, under certain circumstances where none of those explanations would apply. It seems to refer to a gang of international criminals or something of that kind; only—"
"Only what?" I asked, as he hesitated.
"Only that I fancy that it is something on a large scale. Just a little idea of mine, nothing more. Ah, but I must complete my packing. The time advances."
"Don't go," I urged. "Cancel your passage and come out on the same boat with me."
Poirot drew himself up and glanced at me reproachfully.
"Ah, it is that you do not understand! I have passed my word, you comprehend—the word of Hercule Poirot. Nothing but a matter of life or death could detain me now."
"And that's not likely to occur," I murmured ruefully. "Unless at the eleventh hour 'the door opens and the unexpected guest comes in.'"