“What is it, Rolfe?” he asked eagerly.

“This dog has tracked him to the window, so he’s evidently escaped that way,” explained Rolfe briefly.  “He’s climbed along the window-ledge.”

Inspector Chippenfield approached the window and looked out.  A broad window-ledge immediately beneath the window ran the whole length of the building beneath the windows on the fourth floor, and, so far as could be seen, continued round the side of the house.  It was a dizzy, but not a difficult feat for a man of cool head to walk along the ledge to the corner of the house.

“I wonder where that infernal ledge goes to?” said Inspector Chippenfield, vainly twisting his neck and protruding his body through the window to a dangerous extent to see round the corner of the building.  “I daresay it leads to the water-pipe, and the scoundrel, knowing that, has been able to get round, shin down, and get clear away.”

“I’ll soon find out,” said Rolfe.  “I’ll walk along to the corner and see.”

“Do you think you can do it, Rolfe?” asked the inspector nervously.  “If you fell—­” he glanced down to the ground far below with a shudder.

“Nonsense!” laughed Rolfe.  “I won’t fall.  Why, the ledge is a foot broad, and I’ve got a steady head.  He may not have got very far, after all, and I may be able to see him from the corner.”

He got out of the window as he spoke, and started to walk carefully along the ledge towards the corner of the building.  He reached it safely, peered round, screwed himself round sharply, and came back to the open window almost at a run.

“You’re right!” he gasped, as he sprang through.  “I saw him.  He is climbing down the spouting, using the chimney brickwork as a brace for his feet.  If we get downstairs we may catch him.”

He was out of the kitchen in an instant, up the passage, and racing down three steps at a time before the inspector had recovered from his surprise.  Then he followed as quickly as he could, but Rolfe had a long start of him.  When Inspector Chippenfield reached the ground floor Rolfe was nowhere in sight.  The inspector looked up and down the street, wondering what had become of him.

At that instant a tall young man, bareheaded and coat-less, came running out of an alley-way, pursued by Rolfe.

“Stop him!” cried Rolfe, to his superior officer.

Inspector Chippenfield stepped quickly out into the street in front of the fugitive.  The young man cannoned into the burly officer before he could stop himself, and the inspector clutched him fast.  He attempted to wrench himself free, but Rolfe had rushed to his superior’s assistance, and drew the baton with which he had provided himself when he set out from Scotland Yard.

“You needn’t bother about using that thing,” said the young man contemptuously.  “I’m not a fool; I realise you’ve got me.”

“We’ll not give you another chance.”  Inspector Chippenfield dexterously snapped a pair of handcuffs on the young man’s wrists.