Design For Doomsday by Bryce Walton

They were chained to a wall like dumb, dangerous beasts, though such a precaution appeared pitifully unnecessary. At frequent intervals, a contingent of Martian sycophants entered the narrow but high corridor and took a varied number of human slaves through a huge oval door. A door that had once been a gateway of learning into worlds devoted to peace and progressive research. This great structure, now in ruins from the Solar War between Mars and the rest of the System (except the world of the enigmatic Jovians who had remained neutral) had once been known as World Tech. Now it was a huge torture chamber made more hideous because of its modern scientific equipment used for such savage, barbaric research.

There was a terrible kind of silence between these episodes of the opening of the door, except for the half-crazed breathing of resigned humans. But when the oval door opened, screams came out. There were dim, quick impressions of steam and odors. And of shadows that seemed only partly human now, writhing on a wall.