"If I had--" she stopped.

She had been on the point of remarking that she would have known who had stolen and used her theme.
"If you had what ?" asked Arline curiously.
"If I had the genius of which Arline prattles, I'd be at the head of the New York Detective Bureau," finished Grace.

And Anne alone knew that Grace had purposely substituted this flippant answer to conceal her real thought..