Artemis is the leader of the Hunters of Artemis, a group of female warriors who assist Percy and his friends in their quest to rescue her from the Titan Atlas. She also plays a crucial role in the final battle.
Artemis participates in the defense of Olympus against the Titan army, and helps Thalia, the lieutenant of the Hunters, to confront her traitorous father Zeus.
Artemis is mentioned as the patron of Jason's sister Thalia, who is still a Hunter, and as the goddess who sent the prophecy of seven demigods who will face a new threat.
Artemis is one of the Olympians who are incapacitated by a curse from the earth goddess Gaea, and her twin brother Apollo seeks her help to break it. She also appears in a dream to Reyna, the praetor of the Roman camp, and gives her a hint about the Athena Parthenos.
Artemis is one of the Olympians who join the final battle against the giants, and praises the efforts of the demigods and the Hunters. She also blesses Nico, the son of Hades, for his bravery and loyalty.