The Clans are in turmoil. ShadowClan has turned its back on StarClan and pledged to follow the dark predictions of Sol, the strange cat who foretold the solar eclipse. But not all the cats have lost faith in their warrior ancestors...

Jaypaw is convinced that StarClan still holds an important place in the warrior code, and his search for answers leads him far back into the past, farther back than even StarClan can remember. Lionblaze, tortured by violent dreams and bloody visions, wishes he had never been prophesied to be one of the three, but to turn his back on his littermates would be the ultimate betrayal. And Hollyleaf is terrified that once the Clans lose their faith, the warrior code will fall apart. She's willing to fight tooth and nail to preserve it—whatever the cost.

And when murder stalks into the heart of ThunderClan, the cats realize that the darkest shadows don't always lie outside the territory.

The three children of Squirrelflight and Brambleclaw, grandchildren of the great leader Firestar, have thrived in their apprenticeships: Lionpaw's strength and energy serve him well as a warrior in training, Hollypaw hones her understanding of the warrior code, and Jaypaw explores his mysterious powers and connection to StarClan as the medicine cat apprentice.

With more experience comes both power and danger: Lionpaw makes a friendship—and a discovery—that must be kept hidden; Jaypaw learns a secret that could benefit ThunderClan by damaging others; and Hollypaw knows something that could avert a battle, if she could convince the rest of her Clan.

The three are torn apart as each discovers darkness: in themselves, in the Clans, and in the past. And, as conflict begins over what it means to be a warrior, rising tensions threaten to overflow, washing away the peace that has existed for many moons.