All this I had said to myself, and was preparing to carry out my resolution, when I suddenly felt myself seized from behind.

Two men held me by the arms, and another appeared in front of me.

Before I had time to cry out the man exclaimed in English: 

“Hush! not a word!  Are you not Simon Hart?”

“Yes, how did you know?”

“I saw you come out of your cell.”

“Who are you, then?”

“Lieutenant Davon, of the British Navy, of H.M.S. Standard, which is stationed at the Bermudas.”

Emotion choked me so that it was impossible for me to utter a word.

“We have come to rescue you from Ker Karraje, and also propose to carry off Thomas Roch,” he added.

“Thomas Roch?” I stammered.

“Yes, the document signed by you was found on the beach at St. George——­”

“In a keg, Lieutenant Davon, which I committed to the waters of the lagoon.”

“And which contained,” went on the officer, “the notice by which we were apprised that the island of Back Cup served as a refuge for Ker Karraje and his band—­Ker Karraje, this false Count d’Artigas, the author of the double abduction from Healthful House.”

“Ah!  Lieutenant Davon——­”

“Now we have not a moment to spare, we must profit by the obscurity.”

“One word, Lieutenant Davon, how did you penetrate to the interior of Back Cup?”

“By means of the submarine boat Sword, with which we have been making experiments at St. George for six months past.”

“A submarine boat!”

“Yes, it awaits us at the foot of the rocks.  And now, Mr. Hart, where is Ker Karraje’s tug?”

“It has been away for three weeks.”

“Ker Karraje is not here, then?”

“No, but we expect him back every day—­every hour, I might say.”

“It matters little,” replied Lieutenant Davon.  “It is not after Ker Karraje, but Thomas Roch, we have come—­and you also, Mr. Hart.  The Sword will not leave the lagoon till you are both on board.  If she does not turn up at St. George again, they will know that I have failed—­and they will try again.”

“Where is the Sword, Lieutenant?”

“On this side, in the shadow of the bank, where it cannot be seen.  Thanks to your directions, I and my crew were able to locate the tunnel.  We came through all right, and ten minutes ago rose to the surface of the lake.  Two men landed with me.  I saw you issue from the cell marked on your plan.  Do you know where Thomas Roch is?”

“A few paces off.  He has just passed me, on his way to his laboratory.”

“God be praised, Mr. Hart!”

“Amen, Lieutenant Davon.”

The lieutenant, the two men and I took the path around the lagoon.  We had not gone far when we perceived Thomas Roch in front of us.  To throw ourselves upon him, gag him before he could utter a cry, bind him before he could offer any resistance, and bear him off to the place where the Sword was moored was the work of a minute.