Colonel Henderson frowned.  He stepped a little forward with the air of wishing to exclude the Earl from further speech.

“May I ask, Miss Abbeway,” he began, “whether the small coupe car, standing about a hundred yards down the back avenue, is yours?”

“It is,” she assented, with a little sigh.  “It won’t go.”

“It won’t go?” the Colonel repeated.

“I thought you might know something about cars,” she explained.  “They tell me that two of the sparking plugs are cracked.  I am thinking of replacing them tomorrow morning, if I can get Mr. Orden to help me.”

“How long has the car been there in its present condition, then?” the Colonel enquired.

“Since about five o’clock yesterday afternoon,” she replied.

“You don’t think it possible that it could have been out on the road anywhere last night, then?”

“Out on the road!” she laughed.  “Why, I couldn’t get it up to the garage!  You go and look at it, Colonel, if you understand cars.  Fellowes, the chauffeur here, had a look at the plugs when I brought it in, and you’ll find that they haven’t been touched.”

“I trust,” the Earl intervened, “that my chauffeur offered to do what was necessary?”

“Certainly he did, Lord Maltenby,” she assured him.  “I am trying hard to be my own mechanic, though, and I have set my mind on changing those plugs myself to-morrow morning.”

“You are your own chauffeur, then, Miss Abbeway?” her inquisitor asked.

“Absolutely.”

“You can change a wheel, perhaps?”

“Theoretically I can, but as a matter of fact I have never had to do it.’”

“Your tyres,” Colonel Henderson continued, “are of somewhat unusual pattern.”

“They are Russian,” she told him.  “I bought them for that reason.  As a matter of fact, they are very good tyres.”

“Miss Abbeway,” the Colonel said, “I don’t know whether you are aware that my police are in search of a spy who is reported to have escaped from the marshes last night in a small motor-car which was left at a certain spot in the Salthouse road.  I do not believe that there are two tyres such as yours in Norfolk.  How do you account for their imprint being clearly visible along the road to a certain spot near Salthouse?  My police have taken tracings of them this morning.”

Catherine remained perfectly speechless.  A slow smile of triumph dawned upon her accuser’s lips.  Lord Maltenby’s eyebrows were upraised as though in horror.

“Perhaps,” Julian interposed, “I can explain the tyre marks upon the road.  Miss Abbeway drove me down to Furley’s cottage, where I spent the night, late in the afternoon.  The marks were still there when I returned this morning, because I noticed them.”

“The same marks?” the Colonel asked, frowning.

“Without a doubt the same marks,” Julian replied.  “In one place, where we skidded a little, I recognized them.”