they can entrain there. You will
remember that?"

"Yes, sir."

"You might as well understand what it's all about," said the major. "You
see, we're moving a lot of troops. And it is of the utmost importance for
the enemy to know all about the movement and, of course, just as important
for us to keep them from learning what they want to know. So we are
covering the movement as well as we can. Even if they learn some of the
troops that are going, we want to keep them from finding out everything.
Their spy system is wonderfully complete and we have to take every
precaution that is possible. It is most important that you deliver this
message to Colonel Throckmorton. Repeat it to me exactly," he commanded.

They did so, and, seemingly satisfied, he let them go. But just as they
were leaving, he called them back.

"You'd go back by the underground, I suppose," he said. "I'm not sure that
you can get through for the line is likely to be taken over, temporarily,
at any moment. Take a taxicab--I'll send an orderly with you to put you
aboard. Don't pay the man anything; we are keeping a lot of them outside on
government service, and they get their pay from the authorities."

The orderly led them to the stand, some distance from the station, where
the cabs stood in a long row, and spoke to the driver of the one at the
head of the rank. In a moment the motor was started, and they were off.

The cab had a good engine, and it made good time. But after a little while
Harry noticed with some curiosity that the route they were taking was not
the most direct one. He rapped on the window glass and spoke to the driver
about it.

"Got to go round, sir," the man explained. "Roads are all torn up the
straight way, sir. Won't take much longer, sir."

Harry accepted the explanation. Indeed, it seemed reasonable enough. But
some sixth sense warned him to keep his eyes open. And at last he decided
that there could be no excuse for the way the cab was proceeding. It seemed
to him that they were going miles out of the way, and decidedly in the
wrong direction. He did not know London as well as a boy who had lived
there all his life would have done. But his scout training had given him a
remarkable ability to keep his bearings. And it needed no special knowledge
to realize that the sun was on the wrong side of the cab for a course that
was even moderately straight for Ealing.

They had swung well around, as a matter of fact, into a northwest