Green was helpless, and he knew it. Although he raged inwardly, he knew that it would be unwise to arrest the journalist, though such a course might be justified. Apart from the bad feeling such procedure might create, there was the difficulty of establishing a case without disclosing the object of their journey. It was a dilemma where diplomacy might with advantage be employed. He smiled at the reporter. "Mr. Jerrold, can't we settle this without quarrelling? We're on a queer job, and you might spoil it all by hanging around. Leave us to it, and if there's anything fit for publication you shall have first pull. Don't ask me anything else and I'll promise you that." "Honour?" queried Jerrold. "Honour," repeated Green. "Right you are. Slip off and we'll go back. Ring me up at the office." The steam launch wheeled about as Green took his place in his own boat. Both men were satisfied. Each knew that the other would not go back on his word. The chief inspector's boat caught up with that which carried Foyle and Wrington just below Waterloo Bridge. They were threading the tiers of barges moored on the southern side. The group of detectives, with eyes ceaselessly watchful, passed comments in a low voice. They were not hopeful of finding their quarry yet. The search was merely one of precaution. Now and again one of the boats stopped and a man clambered aboard a barge, dropping back in a few minutes with a shake of the head. Foyle and Green left all this to the river men. They knew the work. But, swift as they were, they made slow progress. Foyle glanced uneasily at his watch. It was already growing dusk, and the lights on the bridges were reflected in fantastic shapes from the dark waters. The superintendent spoke in a low voice to Wrington, who jerked his head in sharp assent. "You're right, sir. If we take the likely one now we can leave the others till we've finished. We'll get on. Let her out, boys." The two boats leapt forward, unobtrusively stealing a course in the shadow of the barges. It was delicate work in the gathering darkness, for many times a lighter swinging at its moorings threatened to crush them; but always they avoided the danger, though to the untrained faculties of Foyle it seemed that the margin of safety was no more than the breadth of a knife blade. At London Bridge they crossed to the northern side, and here the real hunt began. Wrington signalled for the lights to be put out, and they stole forward, two black blotches on the dark water. Once they narrowly escaped running down a Customs' patrol boat, and voices cursed them with vigour out of the gloom. Again, as they were about to pass under a mooring rope, some one yelled to Foyle to duck. The warning came too late, and he would have been swept into the water but that a ready knife severed the rope. Then there was a halt for a little, while the barge was secured again.