St. Bride’s Bay lay between two very dangerous points along the coast. Its south extremity was bounded by the long jagged reef known as the Smuggler’s Reef, whilst its northern limit was formed by the jutting cliff upon which Penarvon Castle had been built, and by those two huge crescent-like projecting rocks, significantly termed the Bull’s Horns, just below the castle walls, with the treacherous silting, shifting bed of quicksand between. For many years now in one turret of the castle there had burned from dusk till dawn a strong, steady light, warning vessels along the coast of this dangerous spot. The lantern-tower, as it was commonly called, had a separate entrance and staircase of its own, and the light was watched and tended by a disabled fisherman, who had been appointed by the late Duchess to the office when unfit for more active work. Although growing old and feeble now, he still clung to his task, and had never been found unfaithful to his post, or unable to fulfil the light duties it imposed upon him. The light in this lantern-tower warned vessels of their exact position, and was a most valuable beacon to them; for as soon as ever they had passed it, it became necessary (if they were passing down Channel) to set the ship’s head almost due east, so as to avoid a dangerous cross current round some sunken rocks out at sea, and to keep for some short distance very near in-shore, the water being at this point very deep, and free from any rock or reef. The plan fermenting in the darkened mind of Saul Tresithny became thus fatally easy. A small body of determined men had only to go to the lantern-tower after the household at the castle had retired to rest, overpower the old custodian, extinguish the light, and light a false beacon farther along the coast--a little to the south of the Smuggler’s Reef--and the thing was done. Any vessel beating down Channel would see the light, would clear it, and then turn sharp towards the land, and upon a dark and moonless night would strike hopelessly, and without a moment’s warning, upon those cruel Bull’s Horns, from whose deadly embrace there would be no escape. The vessel would shatter, the crew and passengers would be sucked into a living tomb. The men bent on plunder would have time to secure for themselves a certain amount of the cargo, but before morning dawned the vessel would in all probability have disappeared utterly and entirely. Saul’s act of purposeless vengeance would be accomplished, and he told himself that he should then have some peace.