"Keeping John Dene under proper observation," suggested Colonel Walton quietly.
"Exactly." Mr. Llewellyn John looked at him quickly.
"He was always guarded."
"Then you——" began Mr. Llewellyn John.
"Our men were tricked."
"Tricked!" Mr. Llewellyn John looked startled.
"Yes," continued Colonel Walton. "McLean was on duty that night. Immediately he saw John Dene hail a taxi, he jumped into his own taxi; but he had hardly started when he was run into by a small runabout, and the other taxi got away."
"But the number of——"
"Fictitious both, the taxi and the run-about. We thought it expedient not to detain the man who ran into McLean," Colonel Walton added.
For nearly a minute Mr. Llewellyn John sat staring at the Chief of Department Z.