, which was at once
recognized as one of the finest in Vera Cruz.

"Do you know who lives here?" asked the officer.

"No, sir," replied Donald.

"I was told it was the residence of one of Huerta's generals,"
said a soldier. "It was pointed out to me the first day we
landed."

"Good!" from the officer. "I shall now have no compunction about
entering the place."

With Donald and a couple of soldiers, the officer approached the
door and gave a vigorous knock.

There was no response and he knocked again.

"Who is there?" finally came a voice, evidently a mozo.

"An American officer. Open the door in the name of the law."

There was a still further delay and then another voice asked:
"How do we know it is an officer?"

"Open and find out, before I force the door."

There was a still further delay.

"It's a good thing we guarded the rear," said Donald. "They are
evidently trying to gain time to spirit Lieut. Grimes away,
thinking it is Gen. Funston."

"True," said the officer. "We'll wait no longer. Corporal, force
the door!"

The corporal placed a small stick of dynamite under the door and
fixed a fuse.

"Step back a little," he said.

All obeyed, when at the instant the door was thrown open and a
hand, in which was an automatic revolver, was thrust out,
directly in the face of the officer.

But quick as was the action, Donald was not taken off his guard.

With a single swift blow he struck the weapon into the air.

At the same instant a fusillade from the rear of the house gave
evidence that the men stationed upon the wall had done their
work.

CHAPTER XXVIII.

BILLIE MAKES A DISCOVERY.

Having released Lieut. Grimes and taken the plotters into
custody, the next task was to locate Strong, the mountebank, and
to solve the mystery of the box.

Outside the one exclamation which Donald had uttered when he
recognized Strong as the third of the plotters, he had not
betrayed his secret to any one, and when Lieut. Grimes told his
story to Gen. Funston and described the American, Donald
vouchsafed no information which might help to apprehend him.

"The plotter told the Mexicans that he could be found at the
Hidalgo Hotel whenever he was wanted," explained Lieut. Grimes.
"While he may have lied about it, I think we should send a force
and try to locate him."

The advice was acted upon and a corporal and four soldiers sent
to the hotel, but to no purpose. No such man was known there.

"Wh