Looking over the glooming river, idly watching the rolling water and the scattered buildings upon the bank, Harry suddenly perceived a small door open in the face of a store or warehouse some few yards to his left. The door was some thirty feet above the river, and gave upon a narrow platform to which goods were hoisted by a crane from barges below. As the door opened, inwards, a head appeared. The owner looked for some time up and down the river, over which darkness was fast falling. All was quiet; no traffic was passing; no craft indeed was to be seen save one small boat, moored to a post on the bank some yards on the other side of the bridge. The head disappeared, but immediately afterwards two men emerged from the doorway, coming sideways through the narrow opening. Between them they carried a large sack which their exertions showed to be heavy. They came to the edge of the platform; they laid their burden down; then, giving a quick look around, with one push they toppled it over, and it fell with a sounding plump into the water. It disappeared below the surface; after a moment the two men returned into the warehouse, and the door was shut. The rivers were such common receptacles of rubbish that Harry would not have given a second thought to this incident but for a certain furtiveness in the manner of the two men. He wondered what the sack contained. All at once he saw it reappear on the surface, several yards nearer to him; the stream was flowing fast in his direction. "’Tis maybe a superfluous dog," he thought, for only an animal was likely to rise after such an immersion. Yet it was large for a dog. The sack came steadily towards him: it was about to pass under the single arch of the bridge: he leant over to watch it: and with a start of amazement saw dimly a white human face. At that same moment the bundle sank again. Harry could not know whether it was man or woman, whether alive or dead, but without an instant’s hesitation he ran to the other parapet, sprang on it, and dived into the river. A drowning man rises three times, he had heard; perhaps there was a chance to save this poor wretch, whoever it might be, and foil his murderers.