“Oh—” Evidently Lang was very ill.

Suddenly, as he saw his companion in the forward seat double, Bob felt the stick waggle against his leg.

In an interval between his spasms of violent pain, Lang held up his two hands alongside his helmet.

It was a signal for Bob to take control.

“All right!” he called, and, with a steady hand, he clutched the stick of the controls in his cockpit, set his feet against the rudder bars, and eased his throttle open to regain speed.

He was not in the least nervous or flurried. He pitied Lang’s cramped stomach and evident suffering, but did not permit it to influence his steady nerve. He had been given enough lessons to know how to hold the craft in level flight. While night flying was not as safe and easy as daytime work, he knew that if he followed the ribbon of lighted highway that ran toward the beacons of the nearest airway, he could always “set down” on the asphalt, if worst came to worst, and if he did smash the trucks, the landing gear, he did not think he would do any more serious damage.

“Had I better set down?” he shouted, gliding for speed as he cut out the engine roar. Lang shook his head and gestured forward. Evidently he was not afraid of any immediate physical collapse and preferred to go on flying to see if he would recover. Bob held on.

He picked up the beacon and, watching Lang’s gestures, swung in a long, banked curve, to head across the wind down the unconfined airway, whose second beacon he could see, far away.

By habit looking around to be sure no other ship was close as he turned, Bob, startled, saw the flying lights of another craft pursuing.

It must be pursuit! It came from the direction they had come. It turned as they turned, only in a more sharpened bank, so as to cut off part of the distance, it seemed to Bob, to close the gap between them.