The story follows the adventures of a man named Guts ("Gatsu" in the japanese dub) as he leads his life as a mercenary.
Initially he is a lone mercenary, however he is spotted by Griffith, leader of he Band of the Hawk, and is soon made to join the group after losing a duel to the same. As time goes on Guts and Griffith travel the land with the Band of the Hawk, serving the Kingdom of Midland so that they may acquire fame and power.
However, after being made to kill the son of the King's brother, Guts tries to leave, only to be stopped by Griffith, who forces Guts to duel for his freedom to leave. Guts wins the duel and leaves, leaving Griffith severly depressed and lost, causing him to go to the King's daughter to have sex with her in his state. The morning after he is arrested by the king's guard and taken prisoner, and the members of the Band of the Hawk are attacked and forced to flee the kingdom.
Eventually Guts meets the Band of the Hawk again, only now they are weak from being on the run. Casca and Guts hatch a plan to free Griffith from the King's prison, which succeeds. However, Griffith tries to flee shortly after his rescue, and by cutting himself unleashes the power of the Behelit by bleeding onto it, causing his rebirth and the slaughter of all of the members of the Band of the Hawk except for Guts and Casca, the latter of whom he rapes and impregnates with a demon child.