Alec's sole thought in driving the Osprey out into the river was to get away. He knew very well that if the lawless men in the cabin should lay hands on him in the dark, and particularly if they suspected that he had overheard any of their conversation, it would go hard with him. They might even murder him. So he drove his little craft through the water as fast as he could scull her.

But when he had put some hundreds of feet between himself and the river bank, and no longer feared immediate harm, he began to think the situation over calmly. He had no doubt that Hardy and his pals were planning to steal the seed-oysters from Captain Rumford's newest bed. But whether or not they meant to dredge them at once, Alec did not know. Now he wished that he had not come away so hastily. If only he had remained a little longer, he might have learned all about the plans the thieves were making. He was almost tempted to go back and listen again. He stopped sculling. Then his better judgment told him that it would be foolish to take a chance like that. This time the thieves might discover him; and if they did, he had no doubt whatever that he would get badly hurt. He already knew all that it was necessary to know. All he needed to do now was to inform Captain Rumford and to keep watch on Hardy's boat, the Shark. Alec smiled grimly as he thought how aptly she was named. Now he remembered that he had passed her on the way up the river. She lay at anchor some distance down-stream.

"Moored her there so he could get away without being observed," muttered Alec to himself.

Alec decided he would go ashore and telephone to the shipper, and then try to discover what the men in the cabin meant to do. He headed the Osprey toward the oyster wharves, but before he had gone a dozen yards, the door of the cabin was thrown open and Alec saw a number of men pass through the doorway. Then the door closed as suddenly as it had opened, and all was dark again. Presently splashing sounds in the water and the rattle of an oar told him that the men were getting into a boat. He had no doubt they would go straight to the Shark. He was directly in their path. There was only one thing to do—get away as fast as he could.

Once more Alec swung the Osprey round. She was so much larger and heavier than the ordinary yawl boat that he could not scull her very fast. He headed straight for the farther bank of the river, his heart beating fast as he listened for sounds of possible pursuit. But no noise broke the stillness and Alec knew that he was undiscovered. He went on. Occasionally he heard a low voice in the darkness, and now he was certain that the men in the boat were heading for the Shark.

When Alec reached the farther bank of the river, he rested on his oar and tried to think what he ought to do. He knew that he ought to talk with Captain Rumford the very first thing. But now he did not want to go to the pier lest he lose track of the men in the yawl. They might board the Shark and sail away while he was in the office telephoning. Then he thought of his wireless. Maybe he could get into communication with Elsa at once, and if he could not, he certainly could a little later. Instantly his decision was taken. He would stay in the Osprey and try to watch the oyster thieves.

At once Alec began to string up his instruments. Practically they were already wired together; for he had removed the little shelf bodily from the Bertha B and put it in the box without detaching the instruments from it. He would have to attach the battery again and rig up an aerial. Immediately Alec fastened the Osprey to a near-by piling. Then he covered the windows of his little cabin so no light could shine out. Finally he entered the cabin and closed the companionway tight. Then he lighted a lamp. In a few minutes he had the shelf with his instruments securely mounted where it could remain. He fastened the battery under a bunk and connected it with the instruments on the shelf. He decided that temporarily he would run his lead-in wire through the doorway. He would fix it permanently when daylight came. So he attached the lead-in wire to the single strand of uninsulated wire he meant to use for his aerial. Then tucking his flash-light and his pliers in his pocket, he extinguished his lamp, opened the cabin door, and went on deck. Attaching one end of his aerial to a halyard, he hoisted it nearly to the top of his mast. Then he fastened the lower end to the tiny bowsprit, so that the wire hung almost parallel with the jib stay. It wasn't much of an aerial, but Alec knew it would answer perfectly well for the work he meant to do with it.

He went inside the cabin and tested the outfit. It worked perfectly. He flashed his light on the cabin clock. It was not yet nine o'clock. He made ready to call the shipper on the wireless telephone, then decided he wouldn't. There really was nothing definite that he could tell him. He could merely communicate his suspicions. After all, Captain Hardy might not be going to rob the oyster-bed. If he alarmed the shipper needlessly, the shipper wouldn't think much of his judgment in future. Alec decided he would try to learn something more before communicating with the shipper. At least he could keep a watch on the Shark.