“The truth may just as well be told,” she interrupted.  “There is nothing to be ashamed of.  It is hideously dull down here, and the life my father has asked me to lead for the last few months has been intolerable.  I never sleep, and I invited Captain Granet to come over here at twelve o’clock last night and take me for a motor ride.  I was dressed, meaning to go, and Captain Granet came to fetch me.  It turned out to be impossible because of all the new sentries about the place, but that is why Captain Granet was here, and that,” she concluded, turning to Major Thomson, “is why, I suppose, he felt obliged to tell you what was not the truth.  It has been done before.”

There was a silence which seemed composed of many elements.  Sir Meyville Worth stood with his eyes fixed upon his daughter and an expression of blank, uncomprehending dismay in his features.  Granet, a frown upon his forehead, was looking towards the floor.  Thomson, with the air of seeing nobody, was studying them all in turn.  It was he who spoke first.

“As you justly remark, Miss Worth,” he observed, “this sort of thing has been done before.  We will leave it there for the present.  Will you come this way with me, if you please, Captain Granet?  I won’t trouble you, Miss Worth, or you, Sir Meyville.  You might not like what we are going to see.”

Granet rose at once to his feet.

“Of course, I will come wherever you like,” he assented.

The two men passed together side by side, in momentous silence, across the stone hall, out of the house, and round the back of the garden to a wooden shed, before which was posted a sentry.  The man stood on one side to let them pass.  On the bare stone floor inside was stretched the dead body of Collins.  The salt water was still oozing from his clothes and limbs, running away in little streams.  There was a small blue hole in the middle of his forehead.

“This, apparently,” Thomson said, “is the man who lit the magnesium light which showed the Zeppelin where to throw her bombs.  The thing was obviously prearranged.  Can you identify him?”

“Identify him?” Granet exclaimed.  “Why, I was playing bowls with him yesterday afternoon.  He is a Glasgow merchant named Collins, and a very fine golf player.  He is staying at the Dormy House Club.”

“He has also another claim to distinction,” Major Thomson remarked drily, “for he is the man who fired those lights.  The sergeant who shot him fancied that he heard voices on the creek, and crept up to the wall just before the flare came.  The sergeant, I may add, is under the impression that there were two men in the boat.”

Granet shook his head dubiously.

“I know nothing whatever of the man or his movements,” he declared, “beyond what I have told you.  I have scarcely spoken a dozen words to him in my life, and never before our chance meeting at the Dormy House.”

“You do not, for instance, happen to know how he came here from the Dormy House?”