A BRILLIANT scientist Carlin had set out to study the mysteries of that strange world inside Vulcan which the Futuremen had discovered. He had hired a work-ship with heavy anti-heat equipment to take him to Vulcan, arranging for it to come back there for him in six months.

But when the ship returned it had found no trace of Carlin in the ruined city that had been his base of operations. It had, after a futile search, come back with the news of his disappearance.

All this had happened before the return of the Futuremen from their epoch-making voyage to Andromeda. And now Curt Newton was driving sunward, toward Vulcan, to solve the mystery of Carlin’s fate.

Abruptly, from beyond the bulkhead door of the bridge-room, two voices, one deep and booming, the other lighter and touched with an odd sibilance, were raised in an outburst of argument.

Newton turned sharply. “Stop that wrangling! You’d better get those anti-heaters going or we’ll all fry.”

The door slid open and the remaining members of the unique quartet came in. One of them, at first glance, appeared wholly human — with a lithe lean figure and finely-cut features. And yet in his pointed white face and bright ironic eyes there lurked a disturbing strangeness.

A man but no kin to the sons of Adam. An android, the perfect creation of scientific craft and wisdom — humanity carried to its highest power, and yet not human. He carried his difference with an air but Curt Newton was aware that Otho was burdened with a loneliness far more keen than any he could know himself.

The android said quietly, “Take it easy, Curt. The unit’s already functioning.”

He glanced through the window at the glaring vista of space and shivered. “I get edgy myself, playing around the Sun this close.”

Newton nodded. Otho was right. It was one thing to come and go between the planets, even between the stars. It was a wholly different thing to dare approach the Sun.