Fogerty occupied a table just behind him.

During the meal it occurred to Charlie to telephone to Madame Cerise for
assurance that Louise had arrived safely and without a scene to attract
the attention of strangers. Having finished breakfast he walked into the
telephone booth and was about to call his number when a thought struck
him. He glanced out of the glass door. In the hotel lobby were many
loungers. He saw a dozen pairs of eyes fixed upon him idly or curiously;
one pair might belong to the suspected detective. If he used the
telephone there would be a way of discovering the number he had asked
for. That would not do--not at all! He concluded not to telephone, at
present, and left the booth. His next act was to purchase a morning
paper, and seating himself carelessly in a chair he controlled the
impulse to search for a "scare head" on the abduction of Miss Merrick.
If he came across the item, very well; he would satisfy no critical eye
that might be scanning him by hunting for it with a show of eagerness.
The game was in his hands, he believed, and he intended to keep it
there.

Fogerty was annoyed by the man's evident caution. It would not be easy
to surprise Mershone in any self-incriminating action. But, after all,
reflected the boy, resting comfortably in the soft-padded cushions of a
big leather chair, all this really made the case the more interesting.
He was rather glad Mershone was in no hurry to precipitate a climax. A
long stern chase was never a bad chase.

By and bye another idea occurred to Charlie. He would call upon his
cousin Diana, and get her to telephone Madame Cerise for information
about Louise. It would do no harm to enlighten Diana as to what he had
done. She must suspect it already; and was she not a co-conspirator?