The movement surprised Robert, for he had thought that only Mrs. Vernon and himself had keys to the desk.
"Perhaps he is using Mrs. Vernon's key," he thought.
With great rapidity Frederic Vernon went through several drawers full of papers.
"Pshaw! The papers must be in the safe," he murmured, and leaving the desk he approached the safe, which stood in a corner. Getting down on his knees he began to work at the combination.
"Thirty-five twice, twelve three times," he murmured, repeating what had once been the combination of the lock.
But Mrs. Vernon had had Robert to change the combination just before starting for England, and consequently Frederic Vernon failed to get the door open.
He fussed with the combination for a quarter of an hour, getting more angry over his failure every minute.
"Confound the luck, they must have changed it," he muttered. "I wish I dared to tackle Frost about it. But I am not quite ready for that. Perhaps I can make her give me the combination."
Robert did not hear the last words, yet he felt pretty certain that Frederic Vernon was responsible for his aunt's disappearance, and knew where she was.
He was half of a mind to call in a policeman, yet he was afraid that Vernon might in some manner give the officer of the law the slip.