When this reaches you I shall be beyond the power of human vengeance, for I have determined to end a life which has held so much sorrow and disappointment .-- M." He was satisfied that Mr.Milburgh would not commit suicide, and the information was superfluous that Sam Stay had murdered Mrs.Rider.

It was the knowledge that this vengeful lunatic knew where Odette Rider was staying which made Tarling sweat.
"Where is Mr.Whiteside ?" he asked.
"He has gone to Cambours Restaurant to meet somebody, sir," said the sergeant.
The somebody was one of Milburgh's satellites at Lyne's Store.

Tarling must see him without delay.

The inspector had control of all the official arrangements connected with the case, and it would be necessary to consult him before he could place detectives to watch the nursing home in Cavendish Place.
He found a cab and drove to Cambours, which was in Soho, and was fortunate enough to discover Whiteside in the act of leaving.
"I didn't get much from that fellow," Whiteside began, when Tarling handed him the letter.
The Scotland Yard man read it through without comment and handed it back.
"Of course he hasn't committed suicide.

It's the last thing in the world that men of the Milburgh type ever think about seriously.