“Captain,” Prescott whispered earnestly, “I do not want to arouse any unfair suspicions, but I have something to tell you.  When I first looked over the parapet I noticed on the ground in front three small but distinct glows.  Then came the report and the shell.  Private Berger had stepped into the traverse at his right.  Immediately after the shell burst he came back into this trench.  When I looked over the top a second time I saw the same three tiny glows of light on the ground ahead.  Then came the second shell.  Each time, before the shell was started this way Berger stood with his right hand resting above his head on the parapet.  Each time he stepped down and into the traverse.  Each time, after the shell burst, he stepped back into this trench.  I may be wrong to feel any suspicions, but is it possible-----”

“Wait!” interposed Captain Ribaut quickly, and stepped into the traverse at the left.  He came back with two French soldiers.  These started down the trench, pouncing upon Private Berger.  With them was Captain Ribaut.

“Oh, you scoundrel, Berger!” suddenly hissed the French captain.  He hurled the fellow to the ground, then held up a slim object, some six inches in length.

“See!” he muttered to the others.  “It is a tiny electric light, supplied by a very small special battery.  The scoundrel, Berger, had it concealed up his right sleeve.  Twice he rested his right hand on the parapet.  He flashed the lamp thrice each time, for Captain Prescott saw it.  Then the scoundrel stepped into the traverse, where he would be safe from the shell he had invoked from the enemy.  We have known that there was a spy or a traitor in this regiment, but we were unable to identify him.  Gentlemen, step into the traverses on either side and I will test my belief.”

After the others had filed into the traverses Captain Ribaut rested his right hand on the parapet, causing the little pencil of electric light to glow three times in quick succession.  Then he sprang back into the nearer traverse.

Bang!  A shell landed in the vacated length of trench, tearing up the duck-boards and gouging the walls of the trench.

“Go for your corporal and tell him to send two men to take this spy to the rear,” Ribaut ordered one of the soldiers who stood guarding Berger.  “Captain Prescott, this regiment owes you a debt that it will never be able to repay.  Berger, your hours of life will be short, but the story of your infamy will be everlasting!”

“And, Corporal,” ordered Lieutenant De Verne, after Berger had been started rearward under guard, “see to it that only the most necessary sentries are posted along here for tonight.  Keep the rest of your men in shelters, for the Huns may feel disposed to continue shelling this part of the line.”

“Come, my American comrades,” urged Captain Ribaut, “there is much more to be seen at other points along this line.”