Without a word, Chilverton turned, hurried out to the pavement, and leapt into a taxi-cab that was standing there unengaged.  In another instant the taxi-cab was off, and Allerdyke and Fullaway turned to each other.  Then Allerdyke laughed.

“That’s why Van Koon turned back, Fullaway,” he said in a low voice.  “He recognized Chilverton.  Now, then—­why did that recognition make him run?  And—­who is he?”

CHAPTER XXVIII

THE FIRST PURSUIT

For a moment Fullaway stood in the doorway of the hotel, staring towards the mouth of Kingsway, around the corner of which Chilverton’s cab had already disappeared.  Then he turned, gave Allerdyke a look of absolute non-comprehension, and with a sudden gesture, as of surrender to circumstances, walked into the hotel and made for the stairs.

“That licks everything!” he muttered, as he and Allerdyke went up to the first floor.  “Tell you what it is, Allerdyke—­my poor brain is getting into a whirl!  We’ve had quite enough excitement this morning in all conscience, and now this comes on top of it.  Now, how in creation do you explain this last occurrence?”

Allerdyke laughed cynically.

“I don’t know so much of the world as you do, Fullaway,” he said, “but I don’t think this needs much explanation.  When a man makes himself suddenly scarce at sight of a well-known detective, I should say that man knows the detective wants him—­badly!  My impression is that at this moment your friend Van Koon is running away from Chilverton, and Chilverton’s going hot-foot after him.  And—­”

They were at that moment passing the room which Van Koon had occupied, and Allerdyke suddenly remembered the occasion on which he had seen Mrs. Marlow steal out of it, suspiciously and furtively, and when its proper tenant was away.  He had carefully abstained from telling Fullaway about that little incident, preferring to wait until events had further developed.  Should he tell him now—­now that there seemed to be evidence that Van Koon himself was a doubtful character?  He hesitated—­and while he hesitated Fullaway strode on, flung open his office door, turned to the letter-box at the back, and took out some letters and a telegram.  He tore the telegram open, and the next instant flung it on the table with a fierce exclamation.

“Damn it all, Allerdyke!” he said, waving an indignant hand at the bit of pink paper.  “What in the name of all that’s wicked is the meaning of that?  Read it—­read!”

Allerdyke picked the telegram up and read it aloud.

“Regret shall be unable to return to office for day or two; called away on extremely urgent private business.—­MARLOW.”

He laughed again as he put the telegram back and turned to Fullaway, who, hands plunged deep in pockets and black of countenance, was stamping up and down the room.