"I am acting with you, of course," he answered sullenly, "though I wish you to ask for my help only when it is absolutely necessary. What I complain of is, that I have not been frankly treated, and that I have been placed in an invidious position with Lady Eileen. You must remember that I have feelings, and that it is not pleasant to be told one is acting as a spy, especially by--by an old friend. You know, Mr. Foyle, that I have only been wishful to serve those I have known."

There was something pathetic in his endeavour to justify his actions to himself. Foyle murmured a sympathetic, "I understand--yes, yes, I know,"

and then became thoughtful.

"After all," he said at last, "this does not make us so very badly off.

You are openly on our side now, Sir Ralph, so there can be no fear of your again being accused of acting in an underhand manner. There is nothing more to be done at the moment. I will keep you posted as to any steps we are taking."

"Very well. Good morning, Mr. Foyle."

The baronet was gone. The superintendent resumed his perusal of doc.u.ments. He felt some little compunction at what had happened. Yet it was his business to clear up the mystery, and to use what instruments came to his hand, so long as the law was not violated. There is a code of etiquette in detective work in which the first and most important rule is: "Take advantage of every chance of bringing a criminal to justice." In using Fairfield as an instrument, Foyle was merely following that code.

In a little, Foyle had finished and sent for Green. The chief inspector came with a report.

"A woman brought the advertis.e.m.e.nt to Fleet Street, sir," he said.

"Blake has just telephoned up that he and Lambert are keeping her under observation. He 'phoned earlier that Lady Eileen Meredith had been there."

"Yes, I suppose so. What does the advertis.e.m.e.nt say?"

"He couldn't tell me on the 'phone. He had to hurry away to look after the woman. It is being sent up by taxicab."

"That's good. By the way, Green, keep half-a-dozen men handy, and be about yourself."

"Very good, sir. Is there anything on?"

"I don't quite know. We may have to go out in a hurry. I'll tell you after we have deciphered the advertis.e.m.e.nt."

CHAPTER x.x.xI

It was with an eagerness sternly suppressed that Heldon Foyle took from a messenger the note which he knew contained Grell's advertis.e.m.e.nt.

Although outwardly he was the least emotional of men, he always worked at high tension in the investigation of a case. No astronomer could discover a new comet, no scientist a new element with greater delight than that which animated the square-faced detective while he was working on a case.

He drew out the sheet of paper gingerly between his finger-nails, and tested it with graphite. Eight or nine finger-prints, some blurred, some plain, appeared black against the white surface, and he gave an e.j.a.c.u.l.a.t.i.o.n of annoyance.

"The fools! I warned them to handle it carefully. Now they've been and mixed the whole lot up."

He blew down one of the half-dozen speaking tubes hanging at the side of his desk, and gave a curt order. When Green appeared he was engrossed in copying the advertis.e.m.e.nt on to a writing-pad. He laid down his pen after a while.

"That you, Green? Send this up to Grant, and ask him to have it photographed. See if he can pick out any of the prints as being in the records or bearing on the case. Somebody's been pawing this all over, and the prints are probably spoilt. It's been printed out, too, so there isn't much chance of identifying the writing. Anyhow, we'll have a look more closely at it when the finger-print people have done."

He bent once more to his desk with the copy of the cipher. He knew the key, and it was not necessary to resort to an expert. By the time the chief inspector came back he had a neatly copied translation on his pad.

"Listen to this, Green," he said.

"'E. M. Am now safe on board a barge moored below Tower Bridge, where no one will think of looking for me. Have good friends but little money, owing to action of police. Trust, little girl, you still believe in my innocence, although things seem against me. There are reasons why I should not be questioned. Shall try to embark before the mast in some outward bound vessel. Crews will not be scrutinised so sharply as pa.s.sengers. There are those who will let you know my movements. Fear the police may tamper with your correspondence, but later on when hue and cry has died down will let you know all.'"

The two detectives looked at each other.

"A barge below Tower Bridge," repeated Green, with something like admiration. "That was a good shot. He might have stayed there till doomsday without our hitting on him, or any one taking any notice of him."

"I don't know," said Foyle. "A newcomer on the river would attract attention. These water-men know each other. There's only one way that I can see in which he would avoid being talked about. He is a watchman."

"You're right, sir," agreed the other emphatically. "This is a matter where Wrington of the Thames Division will be able to help us. Hope we can find him at Wapping. Shall I ring through?"

"There's no hurry for a minute or two," said Foyle. "Let's get the hang of the thing right. There's probably some hundreds of barges below Tower Bridge. It will be as well to keep a close eye on the docks and shipping offices. You see, he a.s.serts his innocence."

"H'm," commented Green, with an intonation that meant much. "He says, too, that there are reasons why he shouldn't be questioned."

"Well, we shall see. There had better be an all-station message about the docks. Send two or three men down to Tilbury to watch outgoing boats there. We shan't need any other men from here. Wrington's staff know the river, and will get on best with them. I don't want to leave here until Blake lets us know more about the woman who left the advertis.e.m.e.nt. That gives us another possible clue."

It was some time before Wrington, the divisional detective-inspector at the head of the detective staff of the Thames Division, could be found, for like other branches of the C.I.D. he and his men did their work systematically, and usually left their office at nine o'clock only to return at six. At length, however, he was found at a wharfinger's office, where there had arisen some question of a missing case of condensed milk. Within half an hour he was at Scotland Yard.

A tall man with tired grey eyes, about the corners of which were tiny wrinkles, with a weather-beaten face and grey moustache, he aimed to look something like a riverside tradesman. There was a meekness in his manner and speech that deceived people who did not know his reputation.

He spoke five languages fluently, and two more indifferently. Along the banks of the thirty-five-mile stretch of river for which he was responsible he had waged incessant warfare on thieves and receivers for thirty years, till now practically all serious crime had disappeared.

He it was who, a dozen years before, had fought hand to hand with a naked and greased river thief armed with a knife, in a swaying boat under Blackfriars Bridge; he, too, solved the mystery of a man found dead in the Thames who had been identified by a woman as her husband--a dare-devil adventurer and unscrupulous blackmailer, who was declared by a doctor and a coroner's jury to have been murdered. Step by step he had traced it all out, from the moment when a seaman on a vessel moored at one of the wharves had taken a fancy to bathe, and being unable to swim had fastened a line round his waist and jumped overboard. He had neglected to make the end on board properly fast and was swept away by the current. The rope had twirled round him, and as the body swelled became fixed. A blow on the head from the propeller of a tug completed a maze of circ.u.mstantial evidence which might have served as an excuse to most men for giving up the problem. Yet Wrington had solved it, and the record, which had never seen the light of publicity, was hidden in the archives of the service.

This was the man Foyle had now called in. He stood, with stooping shoulders, nervously twisting his shabby hat, apparently ill at ease.

His nervousness dropped from him like a garment, however, when he spoke. Foyle made clear to him the purport of the excursion they were to embark on.

"Very good, sir," he said. "If you think the man you want is on the river, we will find him. I guess, as you say, he's got a job as a watchman. He's probably had to get somebody to buy a barge, for they don't give these jobs without some kind of reference."

"A reference could easily have been forged. But that doesn't matter. How soon can you get your men together?"

"An hour,--perhaps two. They're scattered all over the place. I sent out to fetch 'em before I left Wapping."

"Three or four will be enough. With Green and yourself and myself we should be able to tackle anything. Have a launch and a motor-boat at Westminster Bridge Pier in a couple of hours' time. If you can borrow them off some one, so that they don't look like police craft, so much the better."

"I can do it, sir."

"Good. In two hours' time, then."

And Heldon Foyle turned away, dismissing the subject from his mind.

Green had gone upstairs to find how Grant of the Finger-print Department had progressed in his scrutiny of the finger-prints on the advertis.e.m.e.nt. He found his specialist colleague with a big enlargement of the paper on which the advertis.e.m.e.nt had been written mounted on paste-board, and propped up in front of him, side by side with an enlargement of the prints found on the dagger.

"Any luck?" asked Green.

Grant shifted his magnifying gla.s.s to another angle and grunted.

"Can't tell yet," he said irritably. "I've only just started. Go away."

"Sorry I spoke, old chap," said the other. "Don't shoot; I'm going."

Grant rested his chin on one elbow and stared sourly at the intruder.