Driven by a profound existential crisis, Karl Glogauer utilizes experimental technology to travel back in time to AD 29, only to discover that the historical reality of the messiah is far more fragile than the myths of his own era. Glogauer, a man adrift in his own time, seeks to resolve his internal conflict regarding his religious heritage by confronting the origins of Christianity directly. His mission is hindered by the stark, brutal reality of ancient Palestine, which contrasts sharply with his idealized expectations. The narrative employs a psychological lens to examine the protagonist's descent into obsession and his eventual acceptance of a grim, self-imposed destiny.

This novel is widely recognized as a seminal work in the New Wave science fiction movement, noted for its willingness to challenge religious orthodoxy through a speculative lens. Critics often highlight the author's ability to blend psychological depth with provocative theological questions, moving beyond standard genre tropes. The work is frequently cited for its stark, unflinching tone, which avoids easy answers regarding the protagonist's motivations or the nature of his sacrifice. Readers often engage with the text as a meditation on the human need for meaning in a secular age, noting that its impact remains potent decades after its initial publication.