with its tubes, its underground stations and taxi-cabs is a pretty difficult proposition."
"I suppose your man lost him in the tube," said McNorton.
"There are two ways down, the elevator and the stairs, and it is mighty difficult to follow a man unless you know which way he is going."
"But you were interrupted at an interesting moment. What are you going to tell us about the Green Rust?"
"I can only tell you this," said Beale, "that the Green Rust is the greatest conspiracy against the civilized world that has ever been hatched."
He looked sharply at Homo.
"Don't look at me," said the Parson, "I know nothing about it, unless" He stopped and frowned. "The Green Rust," he repeated, "is that old man Heyler's secret?"
"He's in it," said Beale shortly.
"Is it a swindle of some kind?" asked the Parson curiously. "It never struck me that Heyler was that kind of man."
"There is no swindle in it so far as Heyler's concerned," said Beale, "it is something bigger than a swindle."
A telephone bell rang and he took up the receiver and listened, only interjecting a query or two. Then he hung up the instrument.
"It is as I thought," he said: "the doctor's slipped again. Had a car waiting for him in Oxford Street and when he saw there were no taxi-cabs about, jumped in and was driven eastward."
"Did you get the number of the car?" asked McNorton.
Beale smiled.
"That's not much use," he said, "he's probably got two or three number-plates."
He looked at his watch.
"I'll go along to Kingston," he said.
"I shan't be able to come with you," said McNorton, "I have a meeting with the commissioner at five."
"Before you go," remarked Beale, "you might put your signature to this declaration of my bona fides."
