nder
their flippers. Orvil bent and took it, lifted it on board, and
continued on his path.

The boys went under again, operating on a prearranged plan. This time
they swam side by side, hands searching for the fish line. Since Rick
knew the approximate position where he had tied it to the projecting
stump, he led the way toward shallow water, hoping to intercept it.

The water shoaled rapidly as the boys approached the shore. Scotty's
hand suddenly gripped Rick's, and Rick felt the line.

At the same instant, Rick was aware of bubbles in the water, a trail of
faint phosphorescence shooting downward past his mask. Then something
glanced from his tank and he heard a sharp clang like a brazen bell in
his ears. The impact rolled him partly over, and as he turned, another
line of phosphorescence streaked past his eyes.

The skin on his back crawled in the blazing moment of recognition. They
were being shot at!

CHAPTER XIII

The Night Watchers

Scotty, who had realized they were being shot at, was pulling at Rick's
arm in frantic jerks, trying to lead him back into deeper water. Rick
needed no urging. His fins thrashed in the shallows as he drove
desperately for the safety of the deepest part of the cove, his hands
keeping contact with the bottom.

The increased pressure on his eardrums told him they had reached the
sanctuary of deeper water where the velocity of bullets would be
absorbed before they could strike. He was bewildered. What had happened?
Who was shooting? For a moment it crossed his mind that Orvil might be
doing the shooting, but he dismissed it. He had no proof that the
crabber hadn't suddenly turned on them; he just didn't believe it.

Yesterday Scotty had seen watchers on the shore, presumably from
Calvert's Favor. Apparently the watchers were there now. The boys had
gone into shallow water, and their tanks had shown above the surface,
drawing fire. It was the only reasonable explanation. Probably the night
watchers had seen the pole handed up to Orvil, or had seen the faint
light reflecting from their masks.

What had happened to Orvil?

One thing was certain. They couldn't stay on the bottom indefinitely.

Rick consulted his wrist compass and closed his fingers on Scotty's
shoulder. He led the way toward the mouth of the cove.

Somewhere on the shore, he thought, the night gunmen were watching the
line of bubbles. The boys' only hope of escaping detection had been to
avoid drawin