In this Book, they arrived at the ocean and found an unusually intelligent badger named Midnight. Midnight told the cats that the Clans would have to leave their forest home and find a new place to live, as humans were going to cut down the forest and build a new "Thunderpath" (the cats' word for a road).

On the return journey, the Clan cats decide, after consultation with Midnight, to go through a mountain range which they had avoided in their initial travels. There, they meet a Clan-like group of cats called the Tribe of Rushing Water, who have their own set of ancestors: the Tribe of Endless Hunting. The Tribe takes the traveling cats in and gives them food and shelter. The Clan cats discover that the Tribe cats have a prophecy: a silver cat will save them from Sharptooth, a savage lion-like creature that has been killing many members of the Tribe. The Tribe thinks that Stormfur is the silver cat from the prophecy, and he is therefore expected to protect the Tribe from Sharptooth. Although reluctant at first, Stormfur eventually agrees to help the Tribe.

Together, the Clan cats succeed in leading Sharptooth into a trap in a cave. However, their plan to poison Sharptooth goes awry, and Feathertail jumps up to the roof of the cave onto a stalactite, causing it to fall. Both Feathertail and Sharptooth are killed by the impact. The Tribe then realizes that Feathertail was the silver cat in their prophecy, not her brother Stormfur, as they had previously thought. The five remaining cats then continue their journey. The book ends with Squirrelpaw noticing Highstones, which is at the edge of WindClan territory; they are almost home.

Meanwhile, back in the forest, the Clans begin to experience the effects of the humans' intrusion into their territories, including lost and poisoned prey, destruction of the forest and cats being abducted.