Dr. William Norden wakes from a catastrophe with shattered memories, stranded on the edge of a war humanity is losing to the mysterious Aliens. Rescued from a damaged outpost and thrust aboard a high-speed military ship, he finds himself under the command of hard-edged officers, watched by a psychiatrist, and haunted by the fear that the real danger may already be inside the human ranks. As alien attacks continue and infiltrators are exposed by brutal fluoroscopic testing, Norden's own odd reactions and memory gaps make him suspect that he may not be entirely himself. Granted a laboratory, a powerful computer, and the help of Pat Miles, General Armsworth's sharp daughter, Norden begins piecing together the notes of his missing colleague Hardwick. The work leads him from war-worn suspicion into a dangerous scientific breakthrough: a possible shield that can hide life itself from alien detection. As he and Pat probe strange clues from paraphysics, Martian sand lizards, and uncanny life-based phenomena, Norden edges closer to understanding both the enemy and the changes within his own mind. In a tense, paranoia-charged battle for identity and survival, the greatest threat may be the unseen force that can turn human beings against themselves. This edition has been fully restored with modern typesetting, custom cover design.