Apollyon is the fifth book in the Left Behind series, which focuses on the events following the Rapture as believers are taken to heaven while the rest of society descends into chaos. The story particularly explores the struggles of the remaining characters as they navigate a world ruled by the Antichrist, Nicolae Carpathia. The novel delves into themes of faith, perseverance, and the moral dilemmas faced by those who remain on earth.
The plot revolves around the Tribulation Force, a group of believers who confront the challenges posed by Carpathia's regime. They undertake covert missions to spread the Gospel and support those persecuted for their faith. The tension builds as they face increasing danger and betrayal, highlighting the stark contrast between the power of evil and the strength of their convictions.