"Drop to a thousand feet, Bill," the scientist called, "and then watch
below. But, don't slow down. We've got to get to Toronto!"

The ship nosed down and soon leveled off at the prescribed altitude.
Van's vacuum tubes lighted to full brilliancy, and a black spot
appeared on the glowing surface just beneath them, a black spot that
extended into a streak as the plane continued on its way. They were
cutting a swath of blackness fifty feet wide through the heart of the
growth!

"See that!" Van gloated. "It's killing them by millions! And the best
of it is the effect it leaves behind. The soil is permeated to a depth
of several inches and the stuff will not germinate in the spots where
the ray has contracted. Oh, it works to perfection!"

Bill was exuberant; his hopes revived miraculously. He gave his motor
the gun and got out of it every last revolution that it could turn up.
He must get Van to Canada! Not such a bad idea, this going after
Kelly, at that!

Bart was voluble in his praise, then caught himself short as he
remembered that he had doubted Van but a half hour previously: doubted
him and despaired. Now Van, lapsing into gloomy silence after his
triumph, was again thinking of nothing but revenge. The getting of Dan
Kelly meant more to him now than the extinction of the moon weed.

* * * * *

When they landed at the Toronto Airport they were welcomed with open
arms instead of with rifle fire as Bill had anticipated. The news had
gone forth. Already a thousand planes flying over the United States
were driving back the sea of destruction. The invisible ray was a
success, and the name of Carl Vanderventer was now a thing with which
to conjure, rather than one on which to heap imprecation and insult.
Van grimaced wryly at this last bit of news.

Danny Kelly? No one at the airport had ever heard of him. Van
telephoned in to the city; to Police Headquarters. Yes, they had
apprehended the fugitive American at the request of Washington, but he
was a slippery customer. He had escaped. Van raged and fumed.

Of what use were the congratulations of the night flyers who still
loitered in the hangar; of what consolation the radio reports of the
success of the ultra-indigo ray in the States and in Europe? He had
come after his man and he'd failed. Defeat was a bitter pill.

The news broadcasts from the States were jubilant and became
increasingly so during the night. The moon weed was be