Professor Fish laughed shortly, a mere bark of sour mirth, and turned to look through the rain-splashed window of the cab.
"Difficult!" he repeated, and turned his face to her again. "Not at all difficult, my dear Miss Pond, but awkward. Lord! it wouldn't do at all!" His eyes behind his glasses became keen and lively. He looked at her carefully.
"He's talked to you, eh? You've heard his story?"
"Yes," answered Mary. "Once; it was very wonderful."
He nodded, still scrutinising her. "I wish I could make him talk," he said thoughtfully. "However——" he shrugged his big shoulders and was silent.
There was a pause then, while the wheels squelched through the mud below, and the rain beat rhythmically on the windows and roof of the cab. Its noise seemed to ally itself to the interior smell of the vehicle, an odor of damp leather and stale straw and ancient stables. The Professor stared intently through the wet glass, and Mary remembered, with a touch of amusement, her first meeting with him, when she had sat beside him and occupied her thoughts with the flabby phantom of Smith.
"You know," she said, at length, "there'll have to be some sort of explanation."
"Well?" demanded the Professor.
"If I knew what you had done to Mr. Smith," she went on, "I could help you to keep things as quiet as possible."
He heard her with a frown and shook his head. "If you knew, you'd do anything but keep it quiet," he answered shortly.