A Case for Dr. Morelle - Act of Violence

Dr. Morelle and Miss Frayle are traveling on the road to visit Professor Stenberg in Lower Ashton. Miss Frayle says " What a lonely road, Dr. Morelle. It's difficult to realize we're only thirty miles from London". Dr. Morelle says "which from my point of view lends it an added attraction". Miss Frayle says "I always think that Essex is a bit cut off. Are you slowing the car?" Dr. Morelle says "I feel positive that I'm following the directions given  to me by Professor Stenberg, but I'm not certain that he gave me the right ones to follow. Professor Stenberg is a trifle absent-minded, while I have reason to remember this locality from a case with which I was concerned". Miss Frayle asks "What was that, doctor?" Morelle says "A rather sorted affair, which wouldn't interest you in the slightest. But, I recall that there was a less devious road than this to Lower Ashton". Miss Frayle says "Oh, there there's a garage ahead. How about asking there?" Morelle stops at the garage, and Miss Frayle says "I'll ask this man. Are we right for Lower Ashton, please?" The man says "Lower Ashton? Oh, you're going the long way round". Miss Frayle asks "What's the matter?" The man says "I, well, that is...." Morelle says "I somehow thought there was a shorter route". The man says "That's right, sir. Yes. Take the second turn on the right, and that will cut off three miles". Miss Frayle says "Oh, you were right, Dr. Morelle, thank you". She turns to the man and says "I'm sorry to have bothered". The man asks "Anywhere in particular you want in Lower Ashton?" Miss Frayle says "Professor Stenberg's house. Perhaps you know it". The man says "With the second right, you can't miss it". Morelle says "Thank you". The man says "Good afternoon, Miss. Good afternoon, doctor". As Morelle pulls the car onto the road again, Miss Frayle says "It was funny, wasn't it?" Morelle says "What, my dear Miss Frayle?" She says "Well, that young man, the sudden look on his face, as if he'd seen a ghost. I believe it had something to do with you".