“But, see here,” demanded Jimmie, stepping forward, “this needs an explanation. Which one of you fellows was at the little cabin on the Holland border?”
Tom Mackinder smiled, in spite of the pain of his crushed leg. He turned his glance toward his brother, whose hand he held.
“We both were there, Jimmie,” he said. “I took the package from the window. You see,” he continued, “it contained plans of my submarine, with which you are familiar. I tried to sell the plans to Germany, but found they had beaten me. So upon my return trip I slipped the package into your baggage, thinking to escape search and detention at the border. I have it here now.”
As he ceased speaking he drew from his pocket the same flat package the boys had seen before.
“Hurrah!” cried Jimmie. “Now we can explain how your brother came to be captured by the Germans, and how under his direction we stole the other ‘U-13’ and escaped from Helgoland.”
“If what you say is true, young man,” put in the officer, “the anticipated court martial may never convene.”
“We can prove it!” protested Jimmie vigorously.
“Then we have solved the Mystery of the ‘U-13’!” declared the officer, with evident relief.
“And now we’ll head for the little old U. S. A. and peaceful neutrality!” was Jimmie’s joyful comment.
“But you’ll first arrange to care for your share of the cargo aboard my boat,” interposed the injured Mackinder.