"All right," I said wearily. "It wasn't. Have it your own way. Some other fool followed a silver-grey Homburg twice round the Park this morning. Some other fool----" A little gasp interrupted me. "But how did you know my number?" "I didn't. I don't. I never could have been about to should. Negatives all the way. It's just chance, my dear. Chance with a Capital J--I mean C. D'you mind if I smoke?" Her reply was preceded by a refreshing gurgle. "Not at all," said my lady. "D'you mean to say you chased us all that way?" "Further. And if it hadn't been for that fire-engine----" "I remember. Wilkins turned down a side-street." "Exactly." "What a shame. Well, if you go to your hatter's you'll get it again." "Your ingenuity is only equalled by your consideration. Isn't that neatly put? You see, I'm writing a letter to _The Observer_, and, when I get going, I can just say things like that one after another." "How wonderful. But I'm afraid I'm interrupting you, and I shouldn't like to deprive Humanity----" "Your name," said I, "is Dot. But I shall call you Mockery. And if you're half as sweet as you sound----" "Good-bye." I protested earnestly. "Please don't say that. We've only just met. Besides ... why was Clapham Common?" "Clapham what?" "No, Common. Why was Clapham Common?" "Well, why was it?" "I can't think, my dear. I thought you might know. It's worried me for years." There was a choking sound, which suggested indignation struggling with laughter. Then-- "I've a good mind to ring off right away," said Dot in a shaking voice. "That would be cruel. Think of the dance you led me this morning. More. Think of the dances you're going to give me on Wednesday week." "Oh, you're going, are you?" "If you are." "What as?" she demanded. "A billiard-marker in the time of Henry the Fourth. And you?" "I can't rise to that. I'm going as myself in a silver frock." "Could anything be sweeter? A little silver Dot. I shall cancel the body-snatcher--I mean billiard-marker--and go as Carry One. Then we can dance together all the evening. By the way, in case I don't hear your voice, how shall I know you?" "A dot," said my lady, "is that which hath position, but no magnitude." "Possibly," said I. "It hath also a dear voice, which, though it be produced indefinitely, will never tire. All the same, in view of the capacity of the Albert Hall, you've not given me much to go on." "As a matter of fact, each of us is going as a parallel line. And that's why I can tell you that I like the sound of you, and--oh, well, enough said." "Thank you, Dot. And why parallel lines?" "They never meet. So long." There was a faint chunk. My lady had rung off. Heavily I hung up my receiver. When the others came in, I was still sitting in the dark at the table, thinking.... * * * * *