A quarter of an hour passed. Both officers realised that in this game of hide-and-seek the U-boat stood a better chance, since she could hear the noisy explosions of the M.L.'s exhausts, especially if she floated motionless with her motors switched off. Again, if it came to a trial of gunnery, the odds were tremendously in favour of the Hun, since the U-boat mounted a couple of 4.7-inch or even 6-inch weapons. Wakefield was counting on the chance of catching his foe napping, and that, if the U-boat were able to dive, she would submerge precipitately. It was then that the depth-charges would play their deadly part. Conscious of a peculiar sinking sensation in the pit of his stomach, Meredith confessed to himself that "he had the wind up." Faced with the possibility of going into action for the first time, he both dreaded and welcomed the chance. Fervently he gave thanks for the fact that it was dark, and that none of his comrades could see his face. For his own part, he felt that every vestige of colour had vanished from his usually bronze features. Again M.L. 1071 was brought to a standstill and recourse made to the hydrophone. The result was disappointing. Except for a faint rumbling that could only be ascribed to the surf lashing the distant cliffs, not a sound was recorded. Apparently the U-boat was again capable of submerging, and was lying doggo on the bed of the North Sea, while the destroyers engaged in hunting her had passed beyond the range of the M.L.'s hydrophone. "We'll just carry on," decided Wakefield. "The fog looks like lifting." Overhead the moonlight was streaming down through a thin layer of mist, while the range of visibility varied from fifty to five hundred yards as banks of dispersing vapour bore down before the light easterly wind. Wiping the moisture from the lenses of his powerful night glasses, Meredith raised the binoculars and scanned the limited expanse of visible sea. Even as he did so a weird greyish object swept across his field of vision. "By Jove!" he ejaculated. "By Jove, what?" asked Wakefield sharply. "Good heavens! Yes, there she is!" He jerked the telegraph indicator to full speed ahead. "See her, Clarkson?" he shouted to the gun-layer. "Two points on your starboard bow. Let her have it." CHAPTER III SUNK IN ACTION A BLINDING flash and a deafening roar, followed by a sickening lurch of the little patrol boat as the lightly built hull reeled to the recoil, announced that the action had commenced. Almost immediately the breech-block of the six-pounder was jerked back and the still smoking metal cylinder clattered noisily on the deck. The air reeked of burnt cordite as the excited gun's crew, who had never before been in action, loaded and fired like men possessed.