Logan paused, looking around at us a little wearily.
"And what aroused your suspicions?" said Smith.
"My suspicions were aroused at the very moment of Sir Baldwin's departure, for as I came out onto the steps with him I noticed a singular thing."
"And that was?" snapped Smith.
"Directly Sir Baldwin had entered the cab the woman got out," replied Logan with some excitement in his manner, "and reclosing the door took her seat beside the driver of the vehicle—which immediately moved off."
Nayland Smith glanced significantly at me.
"The cab trick again, Petrie!" he said; "scarcely a doubt of it." Then, to Logan: "Anything else?"
"This," replied the secretary: "I thought, although I could not be sure, that the face of Sir Baldwin peered out of the window for a moment as the cab moved away from the house, and that there was strange expression upon it, almost a look of horror. But of course as there was no light in the cab and the only illumination was that from the open door, I could not be sure."
"And now tell Mr. Smith," said Weymouth, "how you got confirmation of your fears."
"I felt very uneasy in my mind," continued Logan, "for the whole thing was so irregular, and I could not rid my memory of the idea of Sir Baldwin's face looking out from the cab window. Therefore I rang up the consultant whose name our visitor had mentioned."