k up a few survivors who were clinging to the
floating wreckage.

Then it was that the signals were exchanged and the warships started
towards the island.

The swiftest of them, the _Tonnant_, a French cruiser, forged ahead
while the others forced their draught in an effort to catch up with
her.

The _Tonnant_, at the risk of being blown to pieces in turn,
penetrated the danger zone half a mile, and then ran up her flag while
manoeuvring to bring her heavy guns into action.

From the bridge the officers could see Ker Karraje's band scattered on
the rocks of the island.

The occasion was an excellent one for getting a shot at them before
the bombardment of their retreat was begun, and fire was opened with
the result that the pirates made a rush to get into the cavern.

A few minutes later there was a shock terrific enough to shake the sky
down.

Where the mountain had been, naught but a heap of smoking, crumbling
rocks was to be seen. Back Cup had become a group of jagged reefs
against which the sea, that had been thrown back like a gigantic tidal
wave, was beating and frothing.

What was the cause of the explosion?

Had it been voluntarily caused by the pirates when they realized that
escape was impossible?

The _Tonnant_ had not been seriously damaged by the flying rocks. Her
boats were lowered and made towards all that was left of Back Cup.

The landing parties explored the ruins, and found a few horribly
mangled corpses. Not a vestige of the cavern was to be seen.

One body, and one only, was found intact. It was lying on the
northeast side of the reefs. In one hand, tightly clasped, was a
note-book, the last line of which was incomplete.

A close examination showed that the man was still breathing. He
was conveyed on board the _Tonnant_, where it was learned from the
note-book that he was Simon Hart.

For some time his life was despaired of, but he was eventually brought
round, and from the answers made to the questions addressed to him the
following conclusion was reached:

Moved to his very soul at the sight of the tricolor flag, being at
last conscious of the crime of _lese-patrie_ he was about to commit,
Thomas Roch rushed through the passage to the magazine where a
considerable quantity of his explosive was stored. Then, before
he could be prevented, brought about the terrible explosion which
destroyed the island of Back Cup.

And now Ker Karraje and his pirates have disappeared--and with