"I recollect that there was a policeman on the opposite side of the road. Two youths in evening dress, both far from sober, passed at the moment that we stopped. Stay, now I come to think of it, there was an old woman near us just before we said good-night to each other, and, if my memory serves me, she disappeared down the narrow passage. It is strange that I should have forgotten the circumstance." "An old woman? Can you give me a rather more detailed description of her? Of what class was she?" "Of the very poorest, I should say, and half witted. She was in rags, and was muttering some gibberish to herself. I am afraid I cannot tell you any more about her." "That is rather a pity," said his companion. "I should like to have a little conversation with that good lady." "You surely don't think she had anything to do with the Colonial Secretary's disappearance?" I replied with some surprise. "Why, she couldn't have had sufficient strength to harm a child, much less a strong, active man such as Mr Castellan was." "Perhaps not, sir; it's just possible, however, that she may have had friends to do the work for her. I don't say, of course, that she _had_ anything to do with it, but it is our duty to look after every detail, and my experience has taught me that the most unexpected places often provide the most likely clues. Let us suppose, for instance, that she was only the decoy bird, and that the real perpetrators of the crime were concealed in the passage. As soon as she had discovered Mr Castellan, she passed into the lane and bade her confederates be on the alert; then, when he appeared, they would be ready to effect his capture. Doesn't that plot seem feasible enough, sir?" "Very feasible," I felt compelled to admit; "but your case, like the proverbial figures, can be made to prove anything. However, if you think the old woman had anything to do with it, what action do you propose to take?" "I shall try the street first, and endeavour to discover whether any one heard a scuffle or cries for help last night. Then it's possible the police on the beat may know something of the old woman, and be able to give us an insight into her character and identity. In the meantime, if Mrs Castellan will permit it, I will interview the servants and endeavour to discover whether they noticed any suspicious characters loitering about near the house." "I am sure Mrs Castellan will be only too pleased if you will do what you deem necessary," I replied.