“Keep close to the buildings,” ordered Dave, leading the way toward the sniper.  “I don’t want that fellow to see us until we’re right under him and ready to get him.”

Noiselessly they went up the street.  It would be impossible for the sniper to see them unless he bent out over the edge of the roof from which he was firing.

While they were advancing another shot was fired from the same roof.  Watching the direction of the flash, Darrin was able to guess the direction of the man or men at whom the Mexican was firing.

“Some of our sharpshooters must still be posted on roofs,” Dave whispered over his shoulder to Riley.

“I know one man who won’t be doing much more on a roof, if I can get a sight of him for three seconds,” gruffly answered Riley.

Then they stopped in front of the house in question.

“You slip across to the doorway opposite, and watch for your man,” whispered Darrin.  “I’ll remain here and get any one who may attempt to run out of the house after you open fire.”

Slipping across the street, Riley waited.

Scanning the house, from the roof of which the firing had proceeded, his drawn revolver in his hand, Dave made a quick discovery.

“Why, this is the very door from which I saw Cosetta peering out yesterday!” thought the young ensign.  “I wonder if this is his home in Vera Cruz.  I’ll make a point of reporting this to Trent as soon as we return.”

And then Dave heard a voice just inside the door say, in Spanish: 

“You ought to stop that sniper on the roof.  He took two shots at me as I came up the street.”

“What infernal work is going on here?” Ensign Dave Darrin asked himself, hoarsely.  “I how that voice.  I’d know it anywhere.  That’s Cantor speaking, and he’s in the house of the enemy!”

CHAPTER XIX

A TRAITOR IN THE SERVICE

Crack! spoke a rifle across the street.

“I got him, sir!” cried the exultant voice of Riley.  “But I’ll make sure of him, sir!”

Crack!  The Navy rifle spoke once more.

Noiselessly Darrin darted across the street.

On the roof of the house in which Dave had seen the bandit, Cosetta, the previous day, lay a man, his head and shoulders hanging over the edge.

“Speak softly,” cautioned Darrin.  “I don’t want those men inside the house to hear you.”

“He fell just like that when I fired the first shot, sir,” Riley whispered.  “I sent him the second bullet to make sure that he wasn’t playing ’possum.”

“And now,” Dave ordered, “run down the street as noiselessly as you can go, and tell Lieutenant Trent that I wish he would come here in person, if possible, with a few men.  Ask him, with my compliments to approach as noiselessly as possible, for I expect to make a surprise ‘bag’ here.”

Riley glanced at his officer in swift astonishment, but he saw that Darrin was speaking seriously, so he saluted and departed at a run.