The perspiration poured down the convicts’ faces as they worked, and the warders began to throw anxious glances behind them where Great Tor had already disappeared in an ominous cloud-bank, which rolled down its slopes like cotton-wool. The field in which they were working was the furthest one from the prison, and just above Two Bridges, which lay at the bottom of a steep slope of rough grass. The field was separated from the road by another one, and a high wall without any gates ran down the whole length of the road. The head warder pulled out his watch. It was a quarter to five. He glanced at the low, white clouds which the least puff of wind might at any moment bring down and blot out the landscape. He sounded his whistle, and the convicts at once began to form up and the guard to close in. There was a few moments’ delay while the rakes and forks were collected and the waggon brought up from the end of the field. "Stand next me," No. 303 whispered to Rupert. "Our chance has come. You won’t fail me!" Rupert, whose knowledge of the moor told him that escape was impossible for one as ignorant of his surroundings as poor 303, stooped down to tie his shoelace. "For God’s sake, don’t be a fool! Summer fogs are no good, I can’t——" "No. 381, stand up! All present, chief." The chief warder immediately gave the order to march, and the whole party moved up the centre of the field towards the prison, the warders marching beside their charges and the armed guard about thirty paces away extended so as to completely surround them. Further conversation was rendered impossible. A faint breeze began to stir the still air, bringing a damp mist, which beat in their faces. Rupert, with his eyes fixed on the ground, began to pray that the approaching fog might not blow away. A chance had come—for him. His heart went out in tender sympathy to the poor soul who could not face the long dreary years of his punishment yet to come, while his mind was torn in two by an agony of doubt. He, who knew the moors so well, did not believe for a moment that, alone and unhampered, he could escape; even if they could hide on the moors for a day or two, capture in the end was inevitable. All he wanted was to get to Blackthorn Farm; but 303 wanted to get clear away. Within a few minutes telephones and telegraphs would inform every town and village in the two counties, every railway station would be watched, every egress barred; every constable in Devon and Cornwall would block all roads. Suddenly the voice of the chief warder ordering the convicts to close up broke in upon his thoughts, and looking up he saw that the prison had disappeared—nothing but a white sea of fog lay all around, and even the walls of the field a few yards away were almost invisible! They were only two fields now from the prison, and the gang checked for a moment as the last gate but one was reached.