“A quarter-to-three,” grumbled Stringer.  “There may be murder going on, and here we are."...

A sudden clamor arose upon the shore, near by; a sound as of sledge-hammers at work.  But above this pierced shrilly the call of a police whistle.

“What’s that?” snapped Rogers, leaping up.  “Stand by there!”

The sound of the whistle grew near and nearer; then came a voice—­that of Sergeant Sowerby—­hailing them through the fog.

“Dunbar’s in!  But the gang have escaped!  They’ve got to a motor launch twenty yards down, on the end of the creek"...

But already the police boat was away.

“Let her go!” shouted Rogers—­“close inshore!  Keep a sharp lookout for a cutter, boys!”

Stringer, aroused now to excitement, went blundering forward through the fog, joining the men in the bows.  Four pairs of eyes were peering through the mist, the damnable, yellow mist that veiled all things.

“Curse the fog!” said Stringer; “it’s just our damn luck!”

“Cutter ’hoy!” bawled a man at his side suddenly, one of the river police more used to the mists of the Thames.  “Cutter on the port bow, sir!”

“Keep her in sight,” shouted Rogers from the stern; “don’t lose her for your lives!”

Stringer, at imminent peril of precipitating himself into the water, was craning out over the bows and staring until his eyes smarted.

“Don’t you see her?” said one of the men on the lookout.  “She carries no lights, of course, but you can just make out the streak of her wake.”

Harder, harder stared Stringer, and now a faint, lighter smudge in the blackness, ahead and below, proclaimed itself the wake of some rapidly traveling craft.

“I can hear her motor!” said another voice.

Stringer began, now, also to listen.

Muffled sirens were hooting dismally all about Limehouse Reach, and he knew that this random dash through the night was fraught with extreme danger, since this was a narrow and congested part of the great highway.  But, listen as he might, he could not detect the sounds referred to.

The brazen roar of a big steamer’s siren rose up before them.  Rogers turned the head of the cutter sharply to starboard but did not slacken speed.  The continuous roar grew deeper, grew louder.

“Sharp lookout there!” cried the inspector from the stern.

Suddenly over their bows uprose a black mass.

“My God!” cried Stringer, and fell back with upraised arms as if hoping to fend off that giant menace.

He lurched, as the cutter was again diverted sharply from its course, and must have fallen under the very bows of the oncoming liner, had not one of the lookouts caught him by the collar and jerked him sharply back into the boat.

A blaze of light burst out over them, and there were conflicting voices raised one in opposition to another.  Above them all, even above the beating of the twin screws and the churning of the inky water, arose that of an officer from the bridge of the steamer.