ence of any pursuer. Yet he was convinced that his
every movement was closely watched. It was uncanny, unnerving, this
consciousness of invisible surveillance. Now, as he looked, he started.
The invisible had become the visible.

His cab was just on the point of turning on to the slope of Vauxhall
Bridge. And fifty yards behind, speeding along the Embankment, was a
small French car. The features of the driver he had no time to observe.
But, peering eagerly through the window, showed the dark face of the
passenger. The man's nationality it was impossible to determine, but the
keen, almost savage interest, betrayed by the glittering black eyes, it
was equally impossible to mistake.

If the following car had turned on to the bridge, Harley, even yet,
might have entertained a certain doubt. But, mentally putting himself
in the pursuer's place, he imagined himself detected and knew at once
exactly what he should do. Since this hypothetical course was actually
pursued by the other, Harley's belief was confirmed.

Craning his neck, he saw the little French car turn abruptly and proceed
in the direction of Victoria Station. Instantly he acted.

Leaning out of the window he thrust a ten-shilling note into the
cabman's hand. "Slow down, but don't pull up," he directed. "I am going
to jump out just as you pass that lorry ahead. Ten yards further on
stop. Get down and crank your engine, and then proceed slowly over the
bridge. I shall not want you again."

"Right-oh, sir," said the man, grinning broadly. As a result,
immediately he was afforded the necessary cover, Harley jumped from
the cab. The man reached back and closed the door, proceeding on his
leisurely way. Excepting the driver of the lorry, no one witnessed this
eccentric performance, and Harley, stepping on to the footpath, quietly
joined the stream of pedestrians and strolled slowly along.

He presently passed the stationary cab without giving any sign of
recognition to the dismounted driver. Then, a minute later, the
cab overtook him and was soon lost in the traffic ahead. Even as it
disappeared another cab went by rapidly.

Leaning forward in order to peer through the front window was the
dark-faced man whom he had detected on the Embankment!

"Quite correct," murmured Harley, dryly. "Exactly what I should have
done."

The spy, knowing himself discovered, had abandoned his own car in favour
of a passing taxicab, and in the latter had taken up the pursuit.