Lemaire was forced into the buggy and driven rapidly away.  Once out of sight the Secret Service men turned, driving straight for the local jail.

Before anyone in the excited crowd could ask what had happened the submarine people had vanished.

These four hurried to a room that Mr. Farnum had reserved while they remained at Spruce Beach.

“What was it that rascally Frenchman whispered to you?” demanded the shipbuilder.

Jack promptly repeated the threat, whereat Mr. Farnum’s face grew decidedly grave.

“The worst of it is, Jack, I think the fellow not only meant the threat, but has the connections necessary to carry it out,” said the ship builder, slowly.  “I am quite prepared to believe that these spies work in large groups, when necessary.  I am beginning to think that it will be wise move to get you way from here—­in time.”

“That would give Gaston a fine chance to go clear,” retorted young Benson.  “I am a very important witness when his case comes up.”

“You are also a very important young man for our submarine company,” replied Jacob Farnum, “so important, in fact, that I don’t want to have you put out of this world through any of their plots for revenge.”

“But don’t you see, sir, that, if I run away from here, the fellow Gaston is very likely to be liberated?”

“Let him go, then,” urged Mr. Farnum, though it was plain that he spoke reluctantly.

“It’s just what I won’t do, sir.  I wouldn’t be a good citizen if I should allow a criminal to escape justice just because I was, afraid to stay and testify against him,” argued Captain Jack.

“I admit the force of all you say,” assented Mr. Farnum, slowly.  “Yet, if I should find, after thinking it all over, that it will be best to instruct you to leave here quietly, you won’t refuse to obey, will you?”

“Yes,” declared Jack Benson.

“What?  It would be the first time you ever balked at orders, then.”

“But this is different, Mr. Farnum.  I refuse to obey any order that will tend to defeat the ends of justice.”

Jacob Farnum winced at that statement of the matter.  He had been anxious only to save Jack from the attempts of a dangerous crowd.

“Jack is right,” broke in David Pollard, decisively.

“When he puts the case in that way, I don’t dare say that he isn’t,” admitted the shipbuilder.  “At the same time, I can’t bear the thought of the lad being butchered to gratify the grudge of any of the rascally crew that we’ve offended here at Spruce Beach.”

A slight, rustling sound at the door caused them all to wheel about.  Jacob Farnum’s eyes beheld a slip of white paper lying on the floor, just inside the door.  Jack Benson saw it, also, but he sprang past the paper, pulling the door open.

Around a turn in the corridor the submarine boy heard the sound of fleet footsteps.