The Rebel of Valkyr by Alfred Coppel

Kieron stirred, the pulsing ache in his side piercing the reddish veil of unconsciousness. Under him, he could feel wet stones that stank of death and filth. He moved painfully, and the throbbing agony grew worse, making him teeter precariously between consciousness and the dark.

He was stiff and cold. Hurt badly, too, he thought vaguely. His wounds had not been tended. Very carefully, he opened his eyes. They told him what he had already known. He was in a dark cell, filthy and damp. A sick chill shook him. Teeth chattering, huddled on the stone floor, Kieron sank again into unconsciousness.