Halo: First Strike is a 2003 novel based off the video game Halo: Combat Evolved (2001). By Eric Nylund , it is the story between the first game and its sequel Halo 2. It starts where the game left off, with the Master Chief and Cortana finding a few survivors from the destruction of the ringworld. With valuable information, they must return to Earth and do so by infiltrating The Covenant flagship Ascendent Justice with the help of Covenant Engineers. Once they secure the ship, their first jump is back to Reach, where they pick up surviving UNSC forces, including a few Spartans, and Doctor Halsey. In addition to survivors, they also find that the Covenant have discovered the location of Earth and are about to deploy the entire Covenant fleet. It is revealed by Dr. Halsey that Sergeant Avery J. Johnson survived the Flood encounter because he was diagnosed with Boren's Syndrome, which originated on the fictional planet of Paris IV. The Sarge used a whole crate of plasma grenades long enough for evac to show up, as a result he was rewarded and invested with radiation. The UNSC forces rendezvous with the rebels of the Eridani asteroid field. Dr. Halsey sedates Kelly-087, taking her on her mission that the others do not understand. It presumably relates to the analomy she had that was mentioned the the beginning of the novel. In the be Determined to buy time for Earth to prepare for the inevitable onslaught, the Chief and his Spartans decide to go to the fleet's rendezvous point and disrupt its initial operations in a decisive first strike. John and the rest of his Spartans infiltrate and destroy the Covenant space station, Unyielding Hierophant. They completed their mission, but it cost Grace. The surviving Spartans head back to Earth to warn them of the Covenant's upcoming invasion.

Meanwhile, the High Prophet of Truth and the Brute Chieftain, Tartarus bring forth the incompetent one who lost the Ascendant Justice, who possibly is the Arbiter we play as in Halo 2.