“There is a knob in the floor somewhere there,” Mervyn explained. “Nordhu stamped upon it to raise the flames. If you were to pull it——”

Almost before the words had left his lips Seymour had found the knob he mentioned, a small, round projection in the rocky floor. Grasping it, he gave a mighty tug, and immediately the fire disappeared into its trench, leaving the cell open.

“Jupiter!” gasped Silas as the baronet crossed the threshold, “wherever did you get that rig-out?”

“Explanations must wait,” Seymour returned, rapidly forcing the chains which secured the captives to the wall.

“Where’s Wilson?” he asked an instant later, as he observed that the engineer was absent.

“Heaven alone knows!” replied the scientist. “The priest’s still got him hypnotised, and he’s taken him off somewhere.”

“Hypnotised!” exclaimed Seymour. “Ah, yes. I remember you told me before that Nordhu was a hypnotist. But, wherever Wilson is, we must find him. See here, I have brought some weapons”—unslinging them from his back as he spoke—“do you and Haverly take a sword apiece and make your way out through the temple. Chenobi and I will seek for the engineer.”

At first the two comrades demurred a little at this order, but, on Seymour pointing out that four would be far more likely to attract notice than two, they consented to this arrangement; and, with their weapons ready for action, strode off down the passage. Then the baronet, handing his axe and shield to his Ayuti friend, armed himself with another of the swords, and the twain left the cell. An instant they paused to raise the barrier of fire again by stamping upon the knob that the escape of the prisoners might not be so readily discovered. This done, they moved off on their errand.

As they went, Chenobi, in low tones, gave his friend an account of the method of his capture, telling how Nordhu had cast a spell upon him while he fought at the head of the steps.

“Which road shall we take?” Seymour asked, as they came to the mouth of a gallery.