There was a moment's hesitation.
"Why do you ask?" queried one of the men.
"It is forbidden to pass otherwise."
Again there was a moment's hesitation, and Dan strained his ears to catch the reply.
"We have business with the Commander," said one of the men at last, in a low tone.
The guard was obviously surprised.
"The Commander is very busy," he said, deprecatingly. "Perhaps to-morrow will do."
"To-morrow will not do," was the curt answer.
"I must, at least, announce you," said the guard. "May I have your card?"
A card was produced and handed to him. Without looking at it, he blew a sharp blast on a little whistle which hung about his neck. In a moment another man in uniform appeared at the head of the ladder. The guard mounted and handed him the card.