."

He and the inspector bounded forward along the pier. Fire streaked from
the dark ahead and bullets thumped the rotting boards around them.

Suddenly the loud roar of an accelerated motor drowned out all other
sounds. It came from the river at the pier's end.

Campbell and Ennis reached the end in time to see a long, powerful, gray
motor-boat dash out into the black obscurity of the river, and roar
eastward with gathering speed.

"There they go--they're getting away!" cried the agonized young
American.

Inspector Campbell cupped his hands and shouted out into the darkness,
"River police, ahoy! Ahoy there!"

He rasped to Ennis. "The river police were to have a cutter here
tonight. We can still catch them."

With swiftly rising roar of speeded motors, a big cutter drove in from
the darkness. Its searchlight snapped on, bathing the two men on the
pier in a blinding glare.

"Ahoy, there!" called a stentorian voice over the roar of the motors.
"Is that Inspector Campbell?"

"Yes. Come alongside," yelled the inspector, and as the big cutter shot
close to the end of the pier, its reversing propellers churning the dark
water to foam, Ennis and Campbell leaped.

They landed amid unseen men in the cockpit, and as he scrambled to his
feet the inspector cried, "Follow that boat that just went down-river.
But no shooting!"

* * * * *

With thunderous drumfire from its exhausts, the cutter jerked forward so
rapidly that it almost threw them from their feet again. It shot out
onto the bosom of the dark river that flowed like a black sea between
the banks of scattered lights that were London.

The moving lights of yachts and barges coming up-river could be seen
gliding in that darkness. The captain of the cutter barked an order and
one of his three men, the one crouched at the searchlight, switched its
powerful beam out over the waters ahead.

In a moment it picked up a distant gray spot racing eastward on the
black river, leaving a white trail of foam.

"There she is!" bawled the man at the searchlight. "She's running
without lights!"

"Keep her in the searchlight," ordered the captain. "Sound our siren,
and give the cutter her head."

Swaying, rocking, the cutter roared on through the darkness on the trail
of that distant fleeing speck. As they raced down Blackwall Reach, the
distance between the two craft had already begun to lessen.

"We're overtaking him!" cried Campbell, c