“I agree with you entirely,” replied Seton quietly.  “We must find a boat, and lie off somewhere to watch for George.  He should be worth following.”

“We’ll be moving, then,” said the Leman Street detective.  “It will be high tide in an hour.”

They finished their coffee as quickly as possible; the stuff was not far below boiling-point.  Then Jervis returned the cups to the counter.  “Good night, Pat!” he cried, and rejoined Seton and Kerry.

As they came out into the desolation of the scrap heaps, the last traces of fog had disappeared and a steady breeze came up the river, fresh and salty from the Nore.  Jervis led them in a north-easterly direction, threading a way through pyramids of rubbish, until with the wind in their teeth they came out upon the river bank at a point where the shore shelved steeply downwards.  A number of boats lay on the shingle.

“We’re pretty well opposite Greenwich Marshes,” said Jervis.  “You can just see one of the big gasometers.  The end boat is George’s.”

“Have you searched it?” rapped Kerry, placing a fresh piece of chewing-gum between his teeth.

“I have, sir.  Oh, he’s too wise for that!”

“I propose,” said Seton briskly, “that we borrow one of the other boats and pull down stream to where that short pier juts out.  We can hide behind it and watch for our man.  I take it he’ll be bound up-stream, and the tide will help us to follow him quietly.”

“Right,” said Kerry.  “We’ll take the small dinghy.  It’s big enough.”

He turned to Jervis.

“Nip across to the wooden stairs,” he directed, “and tell Inspector White to stand by, but to keep out of sight.  If we’ve started before you return, go back and join him.”

“Very good, sir.”

Jervis turned and disappeared into the mazes of rubbish, as Seton and Kerry grasped the boat and ran it down into the rising tide.  Kerry boarding, Seton thrust it out into the river and climbed in over the stern.

“Phew!  The current drags like a tow-boat!” said Kerry.

They were being drawn rapidly up-stream.  But as Kerry seized the oars and began to pull steadily, this progress was checked.  He could make little actual headway, however.

“The tide races round this bend like fury,” he said.  “Bear on the oars, sir.”

Seton thereupon came to Kerry’s assistance, and gradually the dinghy crept upon its course, until, below the little pier, they found a sheltered spot, where it was possible to run in and lie hidden.  As they won this haven: 

“Quiet!” said Seton.  “Don’t move the oars.  Look!  We were only just in time!”

Immediately above them, where the boats were beached, a man was coming down the slope, carrying a hurricane lantern.  As Kerry and Seton watched, the man raised the lantern and swung it to and fro.

“Watch!” whispered Seton.  “He’s signalling to the Greenwich bank!”