Part of the Damon Knight Library, republishing all of Damon's books in conjunction with his estate! A physics professor begins to doubt that he is a human being. He imagines that he may have been sent from another world to rescue Earth... or perhaps to destroy it? Solving the mystery takes him far into the future... Damon Knight is a SFWA Grandmaster (indeed, the Grandmaster award is now named the Damon Knight Grandmaster award!) and is the founder of SFWA.