"Stay on duty!" snapped the G.C. speaker. "That's no language known on earth. Those are Martians!"

Thorn looked up to see Sylva standing by the Watch-plane door. Her face was pale in the growing darkness outside.

"Beginning duty sir," said Thorn steadily, "I report that I have with me Miss Sylva West, my fiancée, in violation of regulations. I ask that her family be notified."

He snapped off the lights and went with her. The red rocket-ship had landed in the very next valley. There was a glare there, which wavered and flickered and died away.

"Martians!" said Thorn in fine irony. "We'll see when the Watch planes come! My guess is Com-Pubs, using a searchlight! Nervy!"

The glare vanished. There was only silence, a curiously complete and deadly silence. And Thorn said, suddenly:

"There's no wind!"

There was not. Not a breath of air. The mountains were uncannily quiet. The air was impossibly still, for a mountain-top. Ten minutes went by. Twenty. The detector-whistles shrilled.

"There's the Watch," said Thorn in satisfaction. "Now we'll see!"

And then, abruptly, there was a lurid flash in the sky to northward. Two thousand feet up and a mile away, the unearthly green blaze of a hexynitrate explosion lit the whole earth with unbearable brilliance.