"We shall find out nothing. He was killed by inhaling strong prussic acid. It was jammed right under his nose. Then the murderer went away again, first opening all the windows. Hydrocyanic acid is exceedingly volatile, but it has a pronounced smell of bitter almonds. With no trace of the smell to guide them, and no suspicion of foul play, death would be put down to some natural cause by the doctors. So this man was in the Secret Service, Hastings. And five years ago he disappeared in Russia."
"The last two years he's been in the Asylum," I said. "But what of the three years before that?"
Poirot shook his head, and then caught my arm.
"The clock, Hastings, look at the clock."
I followed his gaze to the mantelpiece. The clock had stopped at four o'clock.
"Mon ami, some one has tampered with it. It had still three days to run. It is an eight-day clock, you comprehend?"
"But what should they want to do that for? Some idea of a false scent by making the crime appear to have taken place at four o'clock?"
"No, no; rearrange your ideas, mon ami. Exercise your little gray cells. You are Mayerling. You hear something, perhaps—and you know well enough that your doom is sealed. You have just time to leave a sign. Four o'clock, Hastings. Number Four, the destroyer. Ah! an idea!"
He rushed into the other room and seized the telephone. He asked for Hanwell.
"You are the Asylum, yes? I understand there has been an escape to-day? What is that you say? A little moment, if you please. Will you repeat that? Ah! parfaitement."