"Halo: First Strike" is a science fiction novel set in the popular Halo universe, written by Eric Nylund. It serves as a bridge between the events of the video game Halo: Combat Evolved and its sequel, Halo 2. The story follows the character Master Chief, a super-soldier known as a Spartan, as he battles against the alien alliance known as the Covenant. The narrative explores the aftermath of the first encounter with the Covenant and delves into the experiences of other key characters, including Cortana, an artificial intelligence. The book provides deeper insights into the lore and background of the Halo series, enriching the overall experience for fans.