Deep in the forest, four Clans of wild cats live and hunt within their respective territories. The novel opens with a territorial dispute between ThunderClan, the forest-dwellers, and RiverClan, the river-dwellers, over Sunningrocks, a place that marks the border on ThunderClan’s side. The ambitious and powerful ThunderClan warrior Tigerclaw fights the RiverClan deputy (second in command) Oakheart. Tigerclaw is frustrated when Redtail, ThunderClan’s deputy, orders the ThunderClan warriors to retreat. Redtail reminds Tigerclaw that their leader, Bluestar, would not want to waste lives, and holds his gaze steadily for a moment. Tigerclaw is still furious and hesitates to obey Redtail, but ultimately complies. Back at ThunderClan’s camp, medicine cat Spottedleaf discusses the current threats facing ThunderClan with Bluestar; Bluestar remarks that the Clan needs more warriors to survive. Spottedleaf receives a prophecy from StarClan, the mystical tribe of departed warrior spirits, when a shooting star blazes across the sky; Spottedleaf interprets the prophecy as “fire alone can save our Clan.”

Rusty, a flame-colored kitten, lives a comfortable life as a house cat to Twolegs (humans) but dreams of adventure in the woods behind his house. He has recurring dreams in which he hunts a mouse, but the mouse evades him every time, leaving Rusty to wake to bland cat food and a restrictive collar around his neck.