Prim, in spite of her protests, had perfect confidence in her twin sister’s ability to handle her plane and whether she was stunting or flying straight. Prim could feel sure of a happy landing and enjoy herself.

At last Terry had worked off her excitement. She leveled out her plane and throttled the engine down to a steady cruising speed. Terry’s success as a flyer was due to the fact that the girl understood her plane thoroughly and treated it with respect. Apart from an occasional burst of speed to work off her excess energy and a few stunts to keep her in practice, Terry kept her plane on a level keel and never overtaxed it.

Mile after mile sped by below them and Terry’s mind was racing ahead to the work she had to do, a mission which might be full of perils and thrilling hazards.

Since the day when her father had started out with such high hopes of success in the venture of The Dick Mapes Flying Field, things had gone all wrong with him. He had obtained an option on a large tract of land at Elmwood from the owner, Peter Langley who lived at a small gold mine in the wilds of Peru, and it was this field that had aroused the envy of his business rival, Joe Arnold.

Most of Dick’s misfortunes had come through the jealousy of this unscrupulous flyer. Joe Arnold was anxious to get control of Dick Mapes’ field, as it was situated near his own and was at a safe point for carrying on his illegal business. If he could once get this field he would be isolated and not run the risk of being seen when loading and unloading his planes.

Joe Arnold was a dangerous rival. He would stop at nothing to carry out his schemes. And for the last two years he had kept Dick Mapes and his helpers in a state of anxiety. At first there had only been slight inconveniences, mishaps that were annoying, but through his agent, Bud Hyslop, who worked as mechanic for Mapes, Joe was able to learn all the plans of the field. He grew bolder and with Bud to carry out his orders, the field was the scene of frequent accidents.

Suspicion pointed to Bud after the crash in which Dick Mapes was injured. Dick was a careful pilot and always checked up on his plane before starting out on a trip. Yet as soon as he was in the air that day, he found that someone had been tampering with his plane. It was too late to save himself. The plane crashed from a height of five hundred feet. It was a miracle that saved Dick from death.

Allan Graham, his young partner, declared that he had seen Bud near the plane just before Dick took off. But no one could say for sure that Bud Hyslop was guilty, although most of the people on the field believed he was. Dick was too tender-hearted to discharge the boy without a reason and it was only after Bud had proven beyond doubt that he was working against the field that Dick let him go.

One thing after another had happened to discredit Dick and for a time it looked as if he might have to give up the field entirely.

And as a final blow word had come from Peter Langley saying that he did not care to extend the option, after he had let it be understood that he would do so. Dick felt as if the struggle was too much for him. Old Peter Langley had gone on to say that he had received reports that Dick was using the field for smuggling purposes, and he did not care to be mixed up with business of that sort.