Feral cats Frostpaw, Sunbeam, and Nightheart process agonizing personal choices while Frostpaw's RiverClan remains leaderless. This third series installment begins as a strong continuation of the previous book, gracefully incorporating plot, meaningful thoughts and conversations, and humor. Nightheart's clever solutions to his future mother-in-law's challenges are especially enjoyable. Adolescent readers will appreciate anthropomorphic angst over finding one's calling and navigating relationships. Should Frostpaw reveal her certainty that her previous visions were not of medicine-cat caliber and instead become a warrior? Is Sunbeam ready for a commitment to Nightheart? Will Nightheart pass difficult tests so he can join ShadowClan? Sadly, after Chapter 16's revelation that StarClan--sky-dwelling, ancestor spirits--disapprove of ShadowClan's occupying RiverClan, the book's quality plummets dramatically, with the last third feeling less carefully presented. More than once the text confusingly uses the tired conceit of a character's dreams to show anxiety--ill-advised in a fantasy series with established ideas about mystical visions. More importantly, the tone precipitously darkens, unraveling earlier gains in insight and decision-making. As ShadowClan escalates its occupation of RiverClan, mistrust and treachery increase. Under the shadow of possible war, Sunbeam and Nightheart vacillate ad nauseum over the newly legalized possibility of switching clans for love; does loyalty belong first to clan or to mate? Nevertheless, established fans will appreciate spending more time with their beloved characters. A mixed bag that starts off well. (lists of clan members, maps) (Fantasy. 11-13) Copyright (c) Kirkus Reviews, used with permission.