At first he was disposed to believe that the sound was due to some other cause, for the deserted wharf was not a likely spot in which to find a dog, but when to the faint whimpering there was added a scratching sound, Seton’s last doubts vanished.

“It’s a dog,” he said, “a small dog.”

Like Kerry, he always carried an electric pocket-lamp, and now he directed its rays into the interior of the building.

A tiny spaniel, whining excitedly, was engaged in scratching with its paws upon the dirty floor as though determined to dig its way through.  As the light shone upon it the dog crouched affrightedly, and, glancing in Seton’s direction, revealed its teeth.  He saw that it was covered with mud from head to tail, presenting a most woe-begone appearance, and the mystery of its presence there came home to him forcibly.

It was a toy spaniel of a breed very popular among ladies of fashion, and to its collar was still attached a tattered and muddy fragment of ribbon.

The little animal crouched in a manner which unmistakably pointed to the fact that it apprehended ill-treatment, but these personal fears had only a secondary place in its mind, and with one eye on the intruder it continued to scratch madly at the floor.

Seton acted promptly.  He snapped off the light, and, replacing the lamp in his pocket, stepped into the building and dropped down upon his knees beside the dog.  He next lay prone, and having rapidly cleared a space with his sleeve of some of the dirt which coated it, he applied his ear to the floor.

In spite of that iron control which habitually he imposed upon himself, he became aware of the fact that his heart was beating rapidly.  He had learned at Leman Street that Kerry had brought Mrs. Irvin’s dog from Prince’s Gate to aid in the search for the missing woman.  He did not doubt that this was the dog which snarled and scratched excitedly beside him.  Dimly he divined something of the truth.  Kerry had fallen into the hands of the gang, but the dog, evidently not without difficulty, had escaped.  What lay below the wharf?

Holding his breath, he crouched, listening; but not a sound could he detect.

“There’s nothing here, old chap,” he said to the dog.

Responsive to the friendly tone, the little animal began barking loudly with high staccato notes, which must have been audible on the Surrey shore.

Seton was profoundly mystified by the animal’s behavior.  He had personally searched every foot of this particular building, and was confident that it afforded no hiding-place.  The behavior of the dog, however, was susceptible of only one explanation; and Seton recognizing that the clue to the mystery lay somewhere within this ramshackle building, became seized with a conviction that he was being watched.

Standing upright, he paused for a moment, irresolute, thinking that he had detected a muffled shriek.  But the riverside noises were misleading and his imagination was on fire.