Who?
Algis Budrys
 In the historical development leading up to the book's plot - a future history at the time of writing, which can now be considered a kind of retroactive alternate history - the Cold War led to the Eastern and Western blocks fusing into two unified super-states during the 1970s and remaining locked in an endless permanent confrontation into the foreseeable future. Actual events seem to have diverged from this scenario with the Sino-Soviet rift and confrontation of the late 1950s and early 1960s, not long after the book's publication. An explosion resulting from an experiment gone awry rocks an Allied research facility near the border with the Soviet Bloc. A Soviet team abducts Dr. Lucas Martino, a leading Allied physicist in charge of a secret, high-priority project called K-88. Several months later, under American pressure, the Communist officials finally hand over an individual, claiming that he is Dr. Martino. The man has undergone extensive surgery for his injuries. He has a mechanical arm advanced beyond any produced in the West. More importantly, his head is now hidden behind a nearly-featureless metal mask. A medical evaluation reveals that several of the man's internal organs are also artificial. The Allies are suspicious that the Soviets have sent them a spy and are holding the real Martino for further interrogation. The struggle to determine the man's true identity is the novel's central conflict. In the end, Shawn Rogers, the agent given the task, is unable to reach a conclusion. The man is released, but kept under surveillance and barred from working on K-88. Later, when progress bogs down on the project, Rogers is sent to ask him to come back to work. The man refuses. Budrys tells the story in alternating chapters. Every second chapter relates part of Lucas Martino's life. The young man spent his formative years on a New Jersey farm, working his way through university in New York City, and graduate studies at MIT. The last part of the novel tells what happened on the Soviet side. It takes many weeks for doctors to save Martino's life. Soviet interrogator Anastas Azarin has little time to work with and is thrown off by the prisoner's expressionless appearance.