"Good-by," he said simply. "I know you will do your best." "Jac! Look there!" I followed Elza's startled gesture to the soft, white clouds which were massed in the sky above us. By what magic of science the thing was accomplished, I know not; but up there in the clouds a gigantic image of Tarrano was materializing! His head and shoulders. Arms folded; his face with a sardonic smile leering down at us! Lips moving. And out of the air about us came his audible, broadcasting words. _"Do your best, my friends!"_ Ironic mockery! _"Coming to conquer Tarrano? Hasten! You are keeping Tarrano waiting most impatiently!"_ The giant voice died away into silence; the huge image melted into the clouds and vanished. Rhaalton looked at us again, expressionless. "Good-by," he repeated. "Do your best." He turned away abruptly. And then as he walked with a despondent droop, I saw his shoulders suddenly straighten. He flung a hand into the air. The signal to start! From a tower in Industriana a puff of violet light shot up to magnify the signal. The girls, all in their places, rose into the air. Draperies fluttering, like graceful birds they rose, circled over us in an arc; and then in a long, single line, with officers apart to one side marking them in squads of twenty, they sped into the dimness of distance. The tower vehicles now were rising. Then the larger platform; the power plant, like a floating building sailing majestically up. "Come, Jac." Elza and Maida were inside the instrument room gazing through one of its windows; and Georg drew me within, closing the transparent door after us. Through the windows I could see the line of vehicles following after the girls. Then our instrument room rose quietly, soundlessly. The ground dropped slowly away, then faster; and as we swung about I saw the hilltop beneath us. Its sides were lined with waving spectators; stricken momentarily with awe at the apparition of Tarrano, they had already forgotten it; from every vantage point of Industriana they were frantically waving. But the hilltop was empty, save for one lone figure--Geno-Rhaalton standing sorrowfully gazing after us. CHAPTER XXXIII _First Assault_ Our spies had informed us that of recent weeks there had arisen about the City of Ice a huge wall behind which Tarrano would make his stand. It was our plan to approach within range of this and establish our power plant as a base from which to direct our offensive. The trip from the Great City was not long. After a few helans our girls ceased flying individually and boarded their appointed vehicles.