Billy had jumped out of the car, and was coming up the steps.
The man raised his hand, and laid it quietly but firmly on my shoulder.
"Then, sir," he said, "it is my duty to arrest you."
There was a short pause.
I looked at him in frank amazement
"Arrest me!" I repeated. "What on earth for?"
The answer came with prompt and startling clearness—
"For the murder of Stuart Northcote."