Hiddenstar died seasons before the fall of StarClan. A hot-headed RiverClan leader out for blood, she drove her Clan into needless battles and conflict under the guise of "protecting RiverClan interests" and keeping the other Clans "in their place." She trained warriors and apprentices hard, valued cruelty and physical strength, and scorned traits she perceived as weaknesses, such as kindness and forgiveness. Over time, her Clan grew increasingly fearful of and hateful toward her, save for a powerful group of loyalists to heeded her every command. Hiddenstar either had no idea of her clanmates' feelings or simply chose to ignore them.

On the night of a gathering, Hiddenstar began throwing insults and threats toward the other Clans, warning of war to come. Things were coming to a head. The RiverClan deputy, Sleeknettle, turned on her and told her to mind her place and to put an end to this campiagn of bloodshed. Furious, Hiddenstar slit his throat in front of the other Clans, and tossed his body in the center of the Fourtrees hollow. She warned her Clanmates that they too would end up like their soft-hearted deputy if they wronged her. The other Clans lashed out at her. A storm began to brew. Hiddenstar ordered her loyalists to attack—only to be struck down by lightning before she had the chance to attack the ThunderClan leader. A silence fell upon the hollow; StarClan demanded the RiverClan be purged of the loyalists, and the rest of the Clans chased them out, where they were never to be seen again. Sleeknettle, who had been unfairly and untimely killed, was resurrected by StarClan and made the new leader of RiverClan.

Hiddenstar awoke in the Dark Forest not in a rage, but in triumph. She was furious at StarClan for turning against her—and vowed her revenge. And although Sleekstar continued to be RiverClan's apologetic and dutiful leader for moons to come, he lived forever in the shadow of Hiddenstar; sleeping with one eye open, always looking over his shoulder, fearful that she would return again.