After discovering that the destiny of the Clans is in their paws, Firestar's three grandchildren face turmoil as ThunderClan is attacked, war breaks out between the Clans, and a mysterious stranger warns of more trouble ahead.

"In the midst of the coldest leaf-bare any warrior can remember, the Clans have lost their connection with their warrior ancestors, and only one ShadowClan apprentice can still hear their voices--or their warning about the new shadow rising within the warrior Clans"--

Struggling to unite the Wild and Leashed Packs for mutual safety after a violent attack, Lucky is cast out by a ruthless Alpha and encounters treacherous elements in the forest and ruined city, which is rapidly enveloped by a poisonous black cloud.

When Firestar's grandchildren, Hollyleaf, Lionblaze, and Jay feather, finally discover who their true parents are, there are dire conseqyences for ThunderClan and the warrior code.

Lucky's efforts to settle in the forest with his fellow Unleashed Dogs is challenged by a fierce wild pack that wants to claim the land, prompting a daring plan by Bella that tests Lucky's cunning and intelligence.