Lenora never finished her sentence.  They had reached the entrance now to the library.  The Professor was standing in the doorway with extended hand, motioning them to take their places at the table.  Then, with no form of warning, the room seemed suddenly filled with a blaze of blue light.  It came at first in a thin flash from the window to the table, became immediately multiplied a thousand times, and played round the table in sparks which suddenly expanded to sheets of leaping, curling flame.  The roar of thunder shook the very foundations of the house—­and then silence.  For several seconds not one of them seemed to have the power of speech.  An amazing thing had happened.  The oak table in the middle of the room was a charred fragment, the chairs were every one blackened remnants.

“A thunderbolt!” French gasped at last.

Quest was the first to cross the room.  From the table to the outside window was one charred, black line which had burnt its way through the carpet.  He threw open the window.  The wire whose course he had followed ended there with a little lump of queer substance.  He broke it off from the end of the wire, which was absolutely brittle, and brought it into the room.

“What is it?” Lenora faltered.

“What have you got there?” French echoed.

Quest examined the strange-looking lump of metal steadily.  The most curious thing about it seemed to be that it was absolutely sound and showed no signs of damage.  He turned to the Professor.

“I think you are the only one who will be able to appreciate this, Professor,” he remarked.  “Look!  It is a fragment of opotan—­a distinct and wonderful specimen of opotan.”

Every one looked puzzled.

“But what,” Lenora enquired, “is opotan?”

“It is a new metal,” Quest explained gravely, “towards which scientists have been directing a great deal of attention lately.  It has the power of collecting all the electricity from the air around us.  There are a dozen people, at the present moment, conducting experiments with it for the purpose of cheapening electric lights.  If we had been in the room ten seconds sooner—­”

He paused significantly.  Then he swung round on his heel.  Craig, a now pitiful object, his hands nervously twitching, his face ghastly, was cowering in the background.

“Your last little effort, Craig?” he demanded sternly.

Craig made no reply.  The Professor, who had disappeared for a moment, came back to them.

“There is a smaller room across the hall,” he said, “which will do for our purpose.”

Craig suddenly turned and faced them.

“I have changed my mind,” he said.  “I have nothing to tell you.  Do what you will with me.  Take me to the Tombs, deal with me any way you choose, but I have nothing to say.”

French smiled a little grimly.

“We may make you change your mind when we get you there,” he remarked.