“Take off your coats and roll up your sleeves,” commanded the inspector.

“You needn’t trouble, Elk.” It was the little chauffeur speaking. “All us boys are good Frogs.”

“There ain’t any good Frogs,” said Elk. “There’s only bad Frogs and worse Frogs and the worst Frog of all. But we won’t argue. Let these men into their cells, sergeant, and keep them separate. I’ll take Litnov to headquarters.”

The chauffeur looked uneasily from Elk to the station sergeant.

“What’s the great idea?” he asked. “You’re not allowed to use the third degree in England.”

“The law has been altered,” said Elk ominously, and re-snapped the handcuffs on the man’s wrists.

The law had not been altered, but this the little Russian did not know. Throughout the journey to headquarters he communed with himself, and when he was pushed into Elk’s bare-looking room, he was prepared to talk. . . .

Dick was waiting for the detective when he came back to Harley Terrace, and heard the story.

“I never dreamt that it was a plant until I spotted the lads waiting for me,” said Elk. “Of course you didn’t telephone; they caught me napping there. Thorough! The Frogs are all that! They expected me to leave headquarters by the Whitehall entrance, and had a taxi waiting to pick me up, but in case they missed me that way, they told off a party to meet me in Harley Terrace. Thorough!”

“Who gave them their orders?”