He nodded. “I only just remembered in time myself. If I’d shot that man the flash from my pistol would have blown us up.”

‘The hangars — they are on fire,” cried Marie Lou excitedly.

They were climbing swiftly now. Far below them, and to the rear, they could see the flames leaping upwards, and in the red glare little dots of men scurrying to and fro. The great arena of the camp was plainly discernible, and, encircling it, the darker ring of the illimitable forest.

A bright shaft of light shot up from one corner of the air-park, followed by another and another from different spots below. “Searchlights,” said the Duke. “They are trying to pick us up. I wonder if they have antiaircraft guns?”

A blinding glare suddenly struck the rapidly climbing plane, making even the interior of the cabin as bright as day. Without warning the ’plane dropped like a stone into the black darkness below. Marie Lou felt a sudden sinking in the pit of her stomach; the blood drained from her face. De Richleau was pitched backwards off his feet.

“We’re hit!” gasped Simon.

The Duke swore softly as he picked himself up off the floor of the cabin. “It’s all right,” he assured them. “Rex is dodging the searchlights.”

As he spoke the ’plane shot forward again. Far above them the beams were now concentrated on a single spot — the place where they had been only a few minutes before. Then they scattered and moved in grid formation across the sky in the same direction as the ’plane.

“Wonder if they’ve got sound detectors?” said Simon. “They’ll pick us up if they have.”

De Richleau shrugged and pointed below. “Rex has tricked them,” he declared. “Look, we are only two hundred feet above the tree tops. Even if they knew our position they couldn’t use their archies — we are below their angle of fire at this distance.”