He vanished through the French windows into the house, leaving Lord Galloway in an indescribable temper, at once virulent and vague.  The blue-and-silver garden, like a scene in a theatre, seemed to taunt him with all that tyrannic tenderness against which his worldly authority was at war.  The length and grace of the Irishman’s stride enraged him as if he were a rival instead of a father; the moonlight maddened him.  He was trapped as if by magic into a garden of troubadours, a Watteau fairyland; and, willing to shake off such amorous imbecilities by speech, he stepped briskly after his enemy.  As he did so he tripped over some tree or stone in the grass; looked down at it first with irritation and then a second time with curiosity.  The next instant the moon and the tall poplars looked at an unusual sight —­an elderly English diplomatist running hard and crying or bellowing as he ran.

His hoarse shouts brought a pale face to the study door, the beaming glasses and worried brow of Dr. Simon, who heard the nobleman’s first clear words.  Lord Galloway was crying:  “A corpse in the grass—­a blood-stained corpse.”  O’Brien at last had gone utterly out of his mind.

“We must tell Valentin at once,” said the doctor, when the other had brokenly described all that he had dared to examine.  “It is fortunate that he is here”; and even as he spoke the great detective entered the study, attracted by the cry.  It was almost amusing to note his typical transformation; he had come with the common concern of a host and a gentleman, fearing that some guest or servant was ill.  When he was told the gory fact, he turned with all his gravity instantly bright and businesslike; for this, however abrupt and awful, was his business.

“Strange, gentlemen,” he said as they hurried out into the garden, “that I should have hunted mysteries all over the earth, and now one comes and settles in my own back-yard.  But where is the place?” They crossed the lawn less easily, as a slight mist had begun to rise from the river; but under the guidance of the shaken Galloway they found the body sunken in deep grass—­the body of a very tall and broad-shouldered man.  He lay face downwards, so they could only see that his big shoulders were clad in black cloth, and that his big head was bald, except for a wisp or two of brown hair that clung to his skull like wet seaweed.  A scarlet serpent of blood crawled from under his fallen face.

“At least,” said Simon, with a deep and singular intonation, “he is none of our party.”

“Examine him, doctor,” cried Valentin rather sharply.  “He may not be dead.”

The doctor bent down.  “He is not quite cold, but I am afraid he is dead enough,” he answered.  “Just help me to lift him up.”

They lifted him carefully an inch from the ground, and all doubts as to his being really dead were settled at once and frightfully.  The head fell away.  It had been entirely sundered from the body; whoever had cut his throat had managed to sever the neck as well.  Even Valentin was slightly shocked.  “He must have been as strong as a gorilla,” he muttered.