Artemis and Zatanna decide to go partying on Halloween night, only to discover that a youthful assassin, Harm, has set his sights on them. Meanwhile, Miss Martian and Superboy take Kid Flash to their high school Halloween dance.

On his birthday, Kid Flash is forced to go on what is supposed to be a simple delivery mission, rather than battle with the Justice League. However, he soon discovers the mission is anything but simple.