Dan pulled the sock over his stump, then attached the prosthetic leg. He hated the thing. It made his stump ache and the difference in weight threw his balance off. He used to run marathons. Now he was lucky to walk a city block before pain made sweat bead on his forehead.

The doctors told him it took some people that way. Their body never got the message that the limb was gone. He had to live with the pain, or in a wheelchair.

He put on his uniform and made sure everything was ...