He broke off with a sharp intake of his breath. Out in the Sound Cavanaugh had turned suddenly about and was making for shore with a wild splashing haste which told instantly of something wrong. For a second Steve stood rooted to the spot. Then he ran toward the spring-board, pulling off his shirt and jerking at the buckle of his belt. As he paused a moment to kick off his shoes and slide out of the scanty shorts, a shrill, inarticulate cry of horror from Ritter urged him on. It was the cramp, then, just as he had feared. But Cavvy was still keeping up. He was even making progress shoreward in spite of that frantic splashing which wasted so much strength. If he only kept his head—