However, it proved that our vigil was not as long as Holmes had thought it would be. And it ended in a very sudden and extraordinary way. Suddenly, without the least sound to warn us, the garden gate swung open. A lithe, dark figure, as swift and active as an ape, rushed up the garden path. We saw it hurry past the light thrown from over the door and disappear into the black shadow of the house.

There was a long pause, during which we held our breath. Then a very gentle creaking sound came to our ears. The window was being opened. The noise stopped, and again there was a long silence. The fellow was getting into the house. We saw the sudden flash of a dark lantern inside the room. What he sought was evidently not there, for again we saw the flash through another window, and then through another.

'Let's go to the open window. We will nab him as he climbs out.' Lestrade whispered.

But before we could move, the man had emerged again. As he came out into the small patch of light, we saw that he was carrying something white under his arm. He looked stealthily around. The silence of the street reassured him. He turned his back to us and put down what he was carrying. The next moment there was the sound of a sharp tap, followed by a rattling noise. The man was concentrating so hard on what he was doing that he never heard our steps as we crept across the grass.