Chester for the moment put aside all thoughts of Hal.  He considered it his first duty to serve the country for which he had already gone through so much.  Hal was in good hands.  So, walking slowly, Chester and Edna made their way to the house where the girl was living.

“I am not particularly fond of playing eavesdropper,” Chester told the girl, as he stealthily followed her up the stairs; “but it is all in the line of duty, so I guess it is up to me.”

From Miss Johnson’s room could be heard the subdued sounds of voices in the next room.

“Rather unthoughtful of them to discuss such business in such a place, to say the least,” remarked Chester.  “Apparently they forget that even the walls have ears.”

The lad laid his ear to the door between the two rooms.  Edna stood close behind him, and the two listened eagerly.

“Well, then it is all settled,” came a low voice from the room beyond.  “You report to the chief immediately.  I’ll remain here an hour, so that we shall not arouse suspicion by going together.  But tell the chief I shall be on hand in time.”

“Good!” came the reply.  “I suppose all other details have been attended to and that the thing will be pulled off smoothly.  To-morrow night should see the end of Louvain.”

Chester straightened up.

“I must get out of the house before he does,” he told the girl.  “I must follow him.”

“But won’t you be in danger?” protested Edna.  “Why not report to the general at once?”

“No,” the lad declared.  “I must at least find the rendezvous.”

Quickly he slipped from the room, and stepped outside the front door just as a door on the upper floor slammed to.

Chester walked slowly down the street, whistling.

“I hope he comes this way,” he told himself.  “Otherwise, I shall have to do some fast walking.”

Fortune favored the boy.  As he walked slowly along, a man brushed swiftly past him.  Taking care to avoid all pretense of pursuit, Chester followed.

CHAPTER XXII.

Chester discovers A plot.

For half an hour the lad stalked his prey through the streets of the city, winding about here and there until Chester had absolutely lost his sense of direction.  Several times the man turned round and glanced furtively about, but apparently he took no notice of his shadow.

Finally he turned into a crooked little street near the outskirts of the city.  Chester also turned the corner, just in time to see the man descend a pair of steps into the basement of what was apparently an unoccupied house.

The lad hurried up and arrived in time to hear the man give a peculiar knock at the door—­one loud tap, followed by three soft taps, then another loud one.

Chester walked back around the corner, where he stopped to think.

“If only I could get in there,” he said to himself.  “I wonder—­”