The game opens with CIA Agent Irene Lew investigating a secret facility, located in the middle of nowhere. As she investigates, she is confronted by Ryu Hayabusa, the game's protagonist, who threatens to kill her, and chases her. The chase eventually leads to a cliff, where Ryu tells her that no one who has seen that facility will live to tell about it. As she backs away, the cliff under Irene gives, and she plummets to her apparent death. Shortly thereafter, Ryu approaches the facility, musing to himself that he couldn't have done this, and someone is stealing his identity. Ryu decides to invade the facility, seeking answers. After fighting through waves of robotic enemies, Ryu encounters the Mantis Warrior, a heavily armored android with a concealed flamethrower. After defeating the android, Ryu continues his investigation, but is stopped by a mysterious young man named Clancy. Clancy gives Ryu a lead, asking him to head for the "Castle Rock Fortress", and telling him that his "enemy" will have set traps for him.