The Lieutenant-Commander went on deck to conduct operations. He was temporarily senior officer, and it fell to him to issue orders to his two consorts relating to the investigation of the scene of the battleship's exploit.
For two hours the three destroyers cruised over the spot where the two submarines were supposed to have sunk. At length wreckage was found by means of grapnels. It was, of course, much too deep to send a diver down to report; but the spot was buoyed, and served as a base while sweeping operations were proceeded with in the hope of locating the hull of the second unterseeboot. In a very short space of time two operations undertaken for the purpose of destroying the sunken submarine were highly satisfactorily carried out. The first resulted in the release of a small quantity of buoyant wreckage, amongst which was the flagstaff of U75. The second brought to the surface a quantity of oil, showing that a submarine had been sunk there, but the injuries she previously received had not been sufficient to liberate the contents of the heavy oil-tanks. The explosive charge had completed the destruction of U77.
Just before five in the afternoon, the Yealm and her consorts passed the eastern arm of the breakwater in Plymouth Sound and brought up in the Hamoaze. Ross and Vernon, arrayed in borrowed clothes and accompanied by Lieutenant-Commander Devereux, lost no time in going ashore and proceeding to the offices of the Commander-in-Chief.
"You are acting with remarkable discretion," observed the Admiral, when Ross reiterated his desire not to communicate with his home until the spies were safely under lock and key. "Fortunately there ought to be no undue delay, as we have two expert Scotland Yard men investigating a case in the Dockyard. I'll telephone to the Superintendent of Police, and get him to send the officers here at once."
Within ten minutes the officers were ushered into the Commander-in-Chief's presence. Ross and Vernon looked at them with considerable curiosity. It had not before fallen to their lot to come into contact with two real representatives of the famous Scotland Yard. Yet there was little about the appearance to occasion comment. They were not in any way disguised. The taller of the two, who was introduced as Detective-Inspector Ferret, was about forty years of age. His closely cut hair was dark-brown, with a plentiful sprinkling of grey hairs. He wore a beard trimmed naval or "torpedo" fashion, with a moustache. He was dressed in a grey lounge suit, with dark-brown boots and a golfing cap. There was nothing of a piercing nature about his eyes, which were of a deep-grey tint. He seemed to be perpetually beaming; the lines on his face gave one that impression.
His companion, Detective Hawke, was a short, thick-set man of about thirty-five. He was clean-shaven. His features were ruddy and heavy. There was a bulldog look about his jaw that proclaimed him to be a tough customer. His rough, brown, Harris-tweed suit and bowler hat gave him the appearance of a prosperous yeoman rather than a successful tracker of criminals.
"Now, young gentlemen," began Mr. Hawke briskly, after the introductions had been made, "we'll get to business. With your permission, sir" (addressing the Admiral), "I will ask Mr. Trefusis to give me his version of the affair. To save time, I feel certain that Mr. Haye will have no objection to going with my colleague and telling him his story. That, I must explain, is the best way to eliminate any discrepancies. We prefer to make a fair start, and then all ought to go well."
During the next hour Detective-inspector Hawke was very busy. He made no written notes. He relied solely upon his marvellous retentive memory, and it was not long before he was in full possession of the facts of the case.
His next step was to telephone to St. Bedal. From the police there, he learnt that Dr. Ramblethorne was medical officer to the 4th battalion of a west-country regiment, but that he was temporarily detailed to act on the recruiting staff at Wellington.
Hawke thereupon telegraphed to Harwich. The Customs officers there informed him that the Harwich-Flushing boat service had been suspended for nearly a week, owing to the discovery of a hostile mine-field off the Dutch coast. Sailings were to be resumed that night. A man who gave himself out to be a Dutchman, but who answered to the description of von Ruhle, had applied that morning for a permit to leave the country by the night boat. His berth had been booked under the name of Cornelius Vanderhuit.