Having made the staggering discovery, I was determined to thoroughly probe the mystery. The tragedy of old Mr. Courtenay's death had resolved itself into a romance of the most mysterious and startling character. As I crept forward over the grass, mostly on tiptoe, so as to avoid the sound of my footfalls, I tried to form some theory to account for the bewildering circumstance, but could discern absolutely none. Mary was still wearing her mourning; but about her head was wrapped a white silk shawl, and on her shoulders a small fur cape, for the spring night was chilly. Her husband had on a dark overcoat and soft felt hat of the type he always wore, and carried in his hand a light walking-stick. Once or twice he halted when he seemed to be impressing his words the more forcibly upon her, and then I was compelled to stop also and to conceal myself. I would have given much to overhear the trend of their conversation, but strive how I would I was unable. They seemed to fear eavesdroppers, and only spoke in low half-whispers. I noticed how old Mr. Courtenay kept from time to time glancing around him, as though in fear of detection; hence I was in constant dread lest he should look behind him and discover me slinking along their path. I am by no means an adept at following persons, but in this case the stake was so great--the revelation of some startling and unparalleled mystery--that I strained every nerve and every muscle to conceal my presence while pushing forward after them. Picture to yourself for a moment my position. The whole of my future happiness, and consequently my prosperity in life, was at stake at that instant. To clear up the mystery successfully might be to clear my love of the awful stigma upon her. To watch and to listen was the only way; but the difficulties in the dead silence of the night were well-nigh insurmountable, for I dare not approach sufficiently near to catch a single word. I had crept on after them for about a mile, until we were approaching the tumbling waters of the weir. The dull roar swallowed up the sound of their voices, but it assisted me, for I had no further need to tread noiselessly. On nearing the lock-keeper's cottage, a little white-washed house wherein the inmates were sleeping soundly, they made a wide detour around the meadow, in order to avoid the chance of being seen. Mary was well known to the old lock-keeper who had controlled those great sluices for thirty years or more, and she knew that at night he was often compelled to be on duty, and might at that very moment be sitting on the bench outside his house, smoking his short clay. I, however, had no such fear. Stepping lightly upon the grass beside the path I went past the house and continued onward by the riverside, passing at once into the deep shadow of the willows, which effectually concealed me.