se than
to make it hard to follow his course.

At Ealing he and Dick carried out their plan exactly. Dick stayed with the
cab, outside the wall; Harry hurried in. And five minutes after Harry had
gone inside a file of soldiers, coming around from another gate, surrounded
the cab and arrested the driver.

CHAPTER V

ON THE TRAIL

Harry had reached Colonel Throckmorton without difficulty and before
delivering Major French's message, he explained his suspicions regarding
the driver.

"What's that? Eh, what's that?" asked the colonel. "Spy? This country's
suffering from an epidemic of spy fever--that's what! Still--a taxicab
driver, eh? Perhaps he's one of the many who's tried to overcharge me. I'll
put him in the guardhouse, anyway! I'll find out if you're right later,
young man!"

As a matter of fact, and as Harry surmised, Colonel Throckmorton felt that
it was not a time to take chances. He was almost sure that Harry was
letting his imagination run away with him, but it would be safer to arrest
a man by mistake than to let him go if there was a chance that he was
guilty. So he gave the order, and then turned to question Harry. The scout
first gave Major French's message, and Colonel Throckmorton immediately
dispatched an orderly after giving him certain whispered instructions.

"Now tell me just why you suspect your driver. Explain exactly what
happened," he said. He turned to a stenographer. "Take notes of this,
Johnson," he directed.

Harry told his story simply and well. When he quoted the officer's remark
to the cab driver, with the German inversion, the colonel chuckled.

"'You have your way lost!' Eh?" he said, with a smile. "You're right--he
was no Englishman! Go on!"

When he had finished, the colonel brought down his fist on his desk with a
great blow.

"You've done very well, Fleming--that's your name?--very well, indeed," he
said, heartily. "We know London is covered with spies but we had flattered
ourselves that it didn't matter very much what they found, since there was
no way that we could see for them to get their news to their headquarters
in Germany. But now--"

He frowned thoughtfully.

"They might be able to set up a chain of signalling stations," he said.
"The thing to do would be to follow them, eh? Do you think you could do
that? You might use a motorcycle--know how to ride one?"

"Yes, sir," said Harry.

"Live with your parents, do you? Would they let you go? I don't thi