mystery of John Rivière had been set at rest.

John Rivière worried him. Deep down in his being was a keen intuitive
feeling that this mysterious half-brother of the dead man was in some
way linked up with the attainment of his ambitions--to help or to
hinder.

Why had he not come to Monte Carlo as arranged? Why had he sent no line
to Olive to excuse himself? Why had he made no further inquiry about
Clifford Matheson--or had he indeed made some inquiry which might set
him on the track of his brother's disappearance?

It was vital to know how matters stood with this John Rivière before he
could march forward unhesitatingly with the Hudson Bay flotation.

The result of the advertisements in the Paris newspapers was annoying.
Where the shipowner had hoped for one answer--or perhaps a couple
pointing in the same direction--over a dozen had been received. This
meant waste of precious time while Sylvester unravelled them. Over the
'phone Larssen and his secretary had discussed the various answers;
rejected some of them; wired for confirmatory details in respect of
others. Provincial hotel-keepers and railway guards were so keenly "on
the make" that they were ready to swear to identity on the slenderest
basis of fact.

In pursuit of two of the clues, Sylvester travelled as far north as
Valognes in the Cotentin, and as far east as Gérardmer in the
Hautes-Vosges. Both journeys were fruitless, and worse than
fruitless--waste of precious time and energy.