He had an idea.

The fleeing chancellor and his daughter were on the train, and he was certain that his friend Carmichael knew it.
The lights of the city presently vanished, and the long journey began, through the great clefts in the mountains, over gorges, across rivers, along wide valleys, and into the mountains again; a journey of nearly seventy hours.

At each stop Carmichael got out, and every time he returned Hans could read disappointment on his face.

Still he said nothing.

He was an admirable comrade.
By the aid of certain small briberies on the train and in Paris Carmichael gathered, bit by bit, that the destination of the woman he loved was America.