As for what it was, Lanyard was well satisfied that he now held the true
focus of this conspiracy, a secret of the first consequence, far too
momentous to the designs of England to be entrusted, though couched in the
most cryptic cipher ever mind of man devised, even to cables or mails which
England herself controlled.

Solely to prevent this communication from reaching America, Lanyard
believed, Germany had sown mines broadcast in all the waters which the
_Assyrian_ must cross, and had commissioned her U-boats, without fail and
at whatever cost, to sink the vessel if by any accident she won safely
through the mine-fields.

In the effort to steal this secret, German spies had sailed on the
_Assyrian_ knowing well the double risk they ran, of being shot like rats
if found out, of being drowned like neutrals if the ship went down through
the efforts of their compatriots.

It was the zeal of Potsdam's agents, seeking the bearer of this secret,
which had caused the rifling of Miss Brooke's luggage when she fell under
suspicion, thanks to her clandestine way of coming aboard; and through the
same agency young Thackeray had been all but murdered when suspicion, for
whatever reason, shifted to him.

To insure safe transmission of this communication, England had held the
_Assyrian_ idle in port, day after day, while her augmented patrols scoured
the seas, hunting down ruthlessly every submarine whose periscope dared
peer above the surface, and while her trawlers innumerable swept the
channels clear of mines.

To prevent its theft, Lieutenant Thackeray had invented the subterfuge of