And, mind you, I don’t think I shall succeed.  To begin with—­I don’t half believe in the existence of your big Diamond.  It looks to me very much like a hoax from beginning to end.  But granting the existence of the stone, and that it was stolen by your Russian friend, are not the chances a thousand to one either that he has disposed of it long ago, or else that he has hidden it away in some place so safe that the cleverest burglar in London would be puzzled to get at it?  Suppose, for instance, that it is deposited by him at his banker’s:  in that case, what are your expectations worth?  Not a brass farthing.  No, my dear dad, the risk of failure is too great, outweighing, as it does, the chances of success a thousandfold, for me to have the remotest hope of ever fingering the fifteen hundred pounds.  I have, therefore, to appraise my time and services as the hero of a losing cause.  I say the hero; for I certainly consider that I am about to play the leading part in the forthcoming drama—­that I am the bright particular ‘star’ round which the lesser lights will all revolve.  Such being the case, I do not consider that I am rating my services too highly when I name two hundred guineas as the lowest sum for which I am willing to play the part of James Jasmin, footman, spy and amateur detective.”

Again Mr. Deedes gasped for breath.  He opened his mouth, but words refused to come.  He shook his head with a fine tragic air, and wiped his eyes.

“Take an hour or two to consider it,” said the son, indulgently.  “If you agree to my proposition, I shall want it put down in black and white and properly signed.  If you do not agree to it, I start back for town by this night’s mail.”

“James, James, you are one too many for me!” said the old man, pathetically.  “Let us go and dine.”

The first thing Madgin junior did after they got back to the hotel was to place before his father a sheet of note-paper, an inkstand and a pen.  “Write,” he said; and the old man wrote to his dictation:—­

“I, Solomon Madgin, on the part of Lady Chillington, of Deepley Walls, do hereby promise and bind myself to pay over into the hands of my son, James Madgin, the sum of fifteen hundred pounds (L1,500) on the day that the aforesaid James Madgin places safely in my hands the stone known as the Hara Diamond.

“Should the aforesaid James Madgin, from causes beyond his own control, find himself unable to obtain possession of the said Diamond, I, Solomon Madgin, bind myself to reimburse him in the sum of two hundred guineas (L210) as payment in full for the time and labour expended by him in his search for the Hara Diamond.

“(Signed) SOLOMON MADGIN.

          “July 21st, 18—.”

Mr. Madgin threw down the pen when he had signed his name and chuckled quietly to himself.  “You don’t think, dear boy, that a foolish paper like that would be worth anything in a court of law?” he said, interrogatively.