“Brown paper, sealed with black wax!” said Allerdyke, remembering what Chettle had told him.  “Good Lord—­what—­”

“I don’t suppose this is the original brown paper, nor these the original dabs of black wax,” remarked the chief as he produced a pocket pen-knife.  “But this parcel, gentlemen, was recently confided by Miss Slade to the care of the manageress of the Pompadour, to be put in the hotel safe—­from which it was produced to me twenty minutes ago.  And—­I am now going to see what it contains.”

The others sat in absorbed silence while the chief delicately removed the wrappings of the mysterious parcel.  A sheet of brown paper, a sheet of cartridge paper beneath it—­and within these very ordinary envelopings an old cigar-box, loosely tied about with a bit of knotted string.

“Now for it!” said the chief.  “The box contains—­”

He raised the lid as the other two leaned nearer.  A stray ray of sunlight, filtering through the swaying boughs of the hawthorn, shot down on the box as the chief lifted a wad of soft paper and revealed a glittering mass of pearls and diamonds.

“The Princess Nastirsevitch’s jewels!” said the chief softly.  “That’s just what I expected ever since the manageress gave me this parcel.  This, of course, is the parcel which your cousin sent that night from Hull, Mr. Allerdyke.  It fell into Mrs. Marlow’s hands—­alias Miss Slade—­and here it is!  That’s all right.”

The other two men stared at the contents of the cigar-box, then at the chief, then at each other.  A deep silence had fallen—­it was some minutes before Allerdyke broke it.

“All wrong, I should say!” he muttered.  “However, if those are the things—­I only say if, mind—­I suppose we’re a step nearer to something else.  But—­what?”

The chief, who appeared to both of them to be strangely phlegmatic about the whole affair, proceeded to close the box, re-invest it in its wrappings, and tie it about with the original string.

“We are certainly a step nearer to a good deal,” he said, making a neat job of his parcel and patting it affectionately as if he had been a milliner’s apprentice doing up a choice confection.  “And the next thing we do is to take a walk together into Hyde Park.  On the way I will tell you why we are going there—­that is, I will tell you what I know of the reason for such an expedition.  It isn’t much—­but it has certain possibilities.”

The two North-countrymen listened with great curiosity as they marched across the grass towards the tea-house.  Each possessed the North-country love of the mysterious and the bizarre—­this last development tickled their fancy and stirred their imagination.

“What on earth d’ye make out of it all?” asked Allerdyke.  “Gad!—­it’s more like a children’s game of hide-and-seek in an old house of nooks and corners than what I should have imagined police proceedings would be.  What say you, Ambler?”