Davis seemed to start. But it was true. Terry added, "The water was clear. We could see that the packing went on down a long way. Say fifty yards at least." "Y-yes," agreed Davis. "All of that." "So in the top fifty yards, at one time, there were at least twenty thousand tons of fish gathered together. Probably very much more. What _La Rubia_ carried away couldn't be noticed. All those thousands of tons of fish were pushed straight down. Tell me," said Terry, "what would be the point in all those fish being dragged to the bottom? I can't ask who or what did it, or even why. I'm asking, what results from it?" Davis grunted. "My mind stalls on who or what and why. And I'd rather not mention my guesses. I.... No!" He moved abruptly away. The _Esperance_ remained under sail near the patch of sea that had glittered earlier and now looked exactly like any other square mile of ocean. The recorder verified the position by giving out, faintly, the same unpleasant humming noise, either louder or fainter. A soft warm wind blew across the waters. The land was somewhere below the horizon. The reel of recorder-tape ran out. It was notable that there were very few fish sounds to be heard, now. Very few. But the hum continued. Toward morning it stopped abruptly. Then there was nothing out of the ordinary to be observed anywhere. The sun rose in magnificent colorings. The sky was clear of clouds. Again the waves looked like living, leaping, joyous things. Gulls were squawking. Doug came up from belowdecks. He carried some photographic prints in his hand. He'd developed and printed what the gun-cameras had photographed when the mysterious object, or beast, leaped clear of the sea. There were seven different pictures. Four showed flashbulb-lighted sections of empty ocean. One showed a column of sea water rising at fantastic height from the sea. Another one showed the edge of something at the very edge of the film. The seventh picture Terry recognized. It was what he'd seen when the flashbulb of his gun-camera went off. The focus was not sharp. But it was neither a whale nor a blackfish--not even a small one--nor was it a shark. It was not a squid. It was not even a giant manta. The picture was a blurry representation of something unreal made for an unimaginable purpose, under abnormal conditions. Deirdre looked at it over his shoulder. It could be a living creature. It could be ... anything. "You said you didn't like mysteries," commented Deirdre. "Are you sorry you came?" _Four_