along in silence for some distance. Presently the steel span of the great
bridge across the Molton River loomed ahead of them in the darkness.

"There's the bridge," Bob exclaimed.

It appeared ghostly in the dark, the big steel girders taking on weird
and fantastic shapes. A train rushed across its span, roaring and
throwing a shower of sparks high into the air.

"Come on," urged Hugh and scrambled up the embankment.

Bob followed close at his heels and together they made their way towards
the bridge itself. They soon found themselves picking their way on the
open ties above the water; as they were headed west they of course took
the east-bound track. The walking was precarious and they had to pay
close attention to what they were doing, for a misstep might prove fatal.

Suddenly a sharp command to halt startled the two boys. They stopped
short and peered intently about them in the dark.

"Who are you?" demanded a curt voice, and Hugh and Bob saw the figure of
a man in khaki outlined against the skyline. A faint flicker of light
showed a keen-edged bayonet affixed to the gun he carried.

"Who are you!" repeated the voice, strangely familiar in tone to both of
the boys. "Come over here, and keep your hands over your head."

"Harold!" exclaimed Bob suddenly. "Is that you?"

"That you, Bob?" queried Harold, for the guard proved to be Bob's older