His features were swollen so that they were hardly recognizable, and hoarse, panting breaths came from his lungs. He was so far gone that he hardly registered surprise at the advent of the five.

"Where's Axelson?" demanded Nat.

The guard pointed toward the end of the corridor, then let his arm fall. Nat led his men along the half-dark passage.

At the end of the corridor two more guards were on duty, but one was collapsed upon the floor, apparently unconscious, and the other, making a feeble attempt to draw his ray-rod, crumbled into ashes as Brent fired. The five burst through the door.

They found themselves in the banquet-hall. The remnants of the meal were still upon the table, and three Moon men, looking as if they had been poisoned, were writhing on the floor. At the farther end of the hall was another door.

This gave upon a central hall, with a door in each of its four sides, and a blaze of sunlight coming through the crystal roof. The five stopped, baffled. Then of a sudden Axelson's voice broke the silence—his voice, yet changed almost beyond recognition, hoarse, broken, and gasping:

"Try the doors, Nathaniel Lee. Try each door in turn, and then go back. And know that in an instant I can blast you to nothingness where you stand!"

And suddenly there came Madge's voice, "He can't! He can't, Nat. He's dying, and he knows it. I won't let him, and he hasn't got the strength to move."

"Which door?" cried Nat in desperation.

"None of the doors. They're a trick," came Madge's voice. "Go forward and press the grooved panel upon the wall in front of you."