"Can we beat them?" asked Alfred.
"Well," replied Pierre, after some reflection, "the car ahead is a racing Mercedes."
The boys knew what that meant.
"What'll they do if they catch us?" said Ralph, as his eyes expanded and he nervously glanced back.
Pierre merely shook his head and remained silent.
The Mercedes was not gaining, however. The second car was trailing along some distance in the rear.
"Hurrah for Belgium!" shouted Pierre, as he gazed forward intently and nodded in the direction of two low structures which were now plainly visible at the sides of the roadway. The boys saw a distinctive flag on each building.
Pierre's hand was on the throttle as he neared the frontier, but he held the lever without drawing it back, while the car sped on. He gave two blasts on the horn, and repeated the signal.
In Europe every road which crosses the frontier has two sets of guards, one belonging to each country, and it is necessary for every one crossing the line to make a formal entry under the inspection of a government official.