Olive made good her promise at once. She packed her father back to England the very next day, to get to work on the Hudson Bay flotation, and Lars Larssen remained on at Monte Carlo.

Though he had led Olive to believe that he had given in merely to please her, yet his true motive was very different. His feelings towards her held no scrap of passion in them. He knew her as vain, shallow, feverishly pleasure-seeking—a glittering dragon-fly. As a woman she made no appeal to him. But as a tool to serve in the attaining of his ambitions, she might conceivably be highly useful.

His true motive in remaining at Monte Carlo was double-edged—to bring Olive into the orbit of his fascination, and to mark time until the 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.

While Larssen waited eagerly for definite news from his secretary with whom he kept constantly in touch by telegram, news came in unexpected fashion through Olive.

"I've just heard from RiviÈre," she announced. "He's at Arles—down with a touch of fever. That's the reason he hadn't written before. Those scientist people are terribly casual in social matters."

"May I see the letter?" asked Lars Larssen. His reason for asking was a desire to study the man's handwriting and draw conclusions from it. He was a keen student of handwriting.

After he had read through the note he remarked drily: "I guess I can give you another reason."

"For his not writing?"

"Yes.... Cherchez la femme."

"Why do you say that?"

"This note was written by a woman."

"It's a very decided hand for a woman."

"Yes it is. I'd stake big on that. Look at the long crossings to the t's. Look at the way the date is written. Look at the way words run into one another."

Olive examined the letter carefully, and laughed. "You're right," said she. "He's travelling with some woman. Those men who are supposed to be wrapped up in their scientific experiments—you can't trust them far!"

Then she added with a curious touch of conscious virtue: "But he'd no right to get that woman to send a letter to me."

Larssen had noted the printed heading to the letter, "Hotel du Forum, Arles," and he wired at once to Morris Sylvester to proceed to Arles and hunt out further details. It seemed an unnecessary precaution, but the shipowner never neglected the tiniest detail when he had a big scheme to engineer.

His relief at the letter proved short-lived. Late that night came a message from Sylvester:—

"RiviÈre not at Arles and not down with fever. Am following up further clues. Will wire again in the morning."

Larssen did not show this wire to Olive. He had told her nothing of his search for RiviÈre—had not even appeared specially interested in him. But in point of fact his interest in the mysterious half-brother of the dead man was steadily growing with every fresh check to the search. The intuition on which he placed such firm faith told him insistently that John RiviÈre was a factor vital to the fulfilment of his ambitions.

All the morning he looked for the telegram his secretary was to send him. It came in the early afternoon:—

"Have found RiviÈre under extraordinary circumstances. Letter and photograph follow."