“It is incredible!” Nigel exclaimed.  “He was the sanest possible man, and the happiest, and he hadn’t an enemy in the world.”

The physician pointed downwards to the revolver.  Then he unfastened once more the dead man’s waistcoat, opened his shirt and indicated a small blue mark just over his heart.

“That is how he died,” he said.  “It must have been instantaneous.”

Time seemed to beat out its course in leaden seconds whilst they waited for the superintendent from Scotland Yard.  Nigel at first stood still for some moments.  From outside came the cheerful but muffled roar of the London streets, the hooting of motor horns, the rumbling of wheels, the measured footfall of the passing multitude.  A boy went by, whistling; another passed, calling hoarsely the news from the afternoon papers.  A muffin man rang his bell, a small boy clattered his stick against the area bailing.  The whole world marched on, unmoved and unnoticing.  In this sombre apartment alone tragedy reigned in sinister silence.  On the sofa, Lord Dorminster, who only half an hour ago had seemed to be in the prime of life and health, lay dead.

Nigel moved towards the writing-table and stood looking at it in wonder.  The code book still remained, but there was not the slightest sign of any manuscript or paper of any sort.  He even searched the drawers of the desk without result.  Every trace of Atcheson’s dispatch and Lord Dorminster’s transcription of it had disappeared!

CHAPTER III

On a certain day some weeks after the adjourned inquest and funeral of Lord Dorminster, Nigel obtained a long-sought-for interview with the Right Honourable Mervin Brown, who had started life as a factory inspector and was now Prime Minister of England.  The great man received his visitor with an air of good-natured tolerance.

“Heard of you from Scotland Yard, haven’t I, Lord Dorminster?” he said, as he waved him to a seat.  “I gather that you disagreed very strongly with the open verdict which was returned at the inquest upon your uncle?”

“The verdict was absolutely at variance with the facts,” Nigel declared.  “My uncle was murdered, and a secret report of certain doings on the continent, which he was decoding at the time, was stolen.”

“The medical evidence scarcely bears out your statement,” Mr. Mervin Brown pointed out dryly, “nor have the police been able to discover how any one could have obtained access to the room, or left it, without leaving some trace of their visit behind.  Further, there are no indications of a robbery having been attempted.”

“I happen to know more than any one else about this matter,” Nigel urged,—­“more, even, than I thought it advisable to mention at the inquest—­and I beg you to listen to me, Mr. Mervin Brown.  I know that you considered my uncle to be in some respects a crank, because he was far-seeing enough to understand that under the seeming tranquillity abroad there is a universal and deep-seated hatred of this country.”