“Miss Slade!” exclaimed Fullaway.  “What on earth are you talking about?  That’s my secretary, Mrs. Mar—­”

“Sh!” interrupted the chief.  “That’s one of your surprises, Mr. Fullaway!  Quiet, now, quiet.  Our job is to watch.  Something’ll happen in a minute.”

Miss Slade and her talkative companion edged their way through the crowd and passed out to an open patch of grass whereon a few children were playing.  And as they went, two or three men also separated themselves from the idlers around the tables and strolled quietly and casually in the same direction.  Also, Van Koon and the man with him left their table, and, as if they had no object in life but mere aimless chatter and saunter, wandered away towards the couple who had first emerged from the enclosure.  And thereupon, Fullaway, not to be repressed, burst out with another exclamation.

“My God, Chilverton!” he cried.  “There is Van Koon!  And, by all that’s wonderful, Merrifield with him.  Now what—­”

The New York detective, who was under no orders, and knew no reason why he should restrain himself, wasted no time in words.  Like a flash, he had leapt from his chair, threaded his way through the surrounding people, and was after his quarry.  And with a muttered exclamation of anger, the chief rose and followed—­and it seemed to Allerdyke that almost at the same instant a score of men, up to that moment innocently idling and lounging, rose in company.

“Damn it!” he growled, as he and Appleyard got up.  “That chap’s going to spoil everything.  What is he after?  Confound you, Fullaway!—­why couldn’t you keep quiet for a minute?  Look there!”

Van Koon had turned and seen Chilverton.  So, too, had Van Koon’s companion.  So, also, had Miss Slade and the man she was walking with.  That man, too, saw the apparent idlers closing in upon him.  For a second he, and Van Koon, and the other man stared at each other across the grass; then, as with a common instinct, each turned to flee—­and at that instant Miss Slade, with a truly feminine cry, threw herself upon her companion and got an undeniably firm grip on his struggling arms.

“This is the Eastbourne Terrace man!” she panted as Allerdyke and half-a-dozen detectives relieved her.  “Get the other two—­Van Koon and Merrifield.  Quick!”

But Van Koon was already in the secure grip of Chilverton, and the person in the light blue suit was being safely rounded up by a posse of grim-faced men.

CHAPTER XXXIII

THE SMART MISS SLADE