Shadowclan has a dark new leader, Tigerstar, the exiled deputy from ThunderClan. We are left wondering whether he will be satisfied with his power now — or whether his desire for revenge will burn stronger yet? Fireheart, the young ThunderClan deputy, fears that there is a connection between the rise of Tigerstar and the terrible dreams of danger that haunt his dreams. Meanwhile, a mysterious threat has invaded the forest, placing every life in peril. Cats hear the words "Pack, pack," and "kill, kill" uttered everywhere. Swiftpaw is killed by the "pack" and half of Brightpaw's (later Brightheart) face is torn off (She is later given the name "Lostface" by Bluestar). However, Fireheart doesn't have much time to dwell on that because of Bluestar's lack of faith of StarClan and even her own Clan. Fireheart doesn't know if he can convince Bluestarthat ThunderClan cats aren't traitors and save the Clan at the same time. He worries if Bluestar is really out of her mind and wanting to attack WindClan, who Bluestar believes has been stealing ThunderClan's prey. However, Fireheart soon finds a bloodless way of solving the problem. But soon Fireheart find out that a pack of dogs threatens the Clan. Fireheart suspects that Tigerstar has something to do with this. Fireheart finds a way to get the dogs out of the forest once and for all: by leading through the forest and over the gorge. When Fireheart is at the gorge, Tigerstar attacks him, holding him down so that he'll fall victim to the blood-thirsty beasts. Just at the last moment, Bluestar comes in out of thin air, slamming into the lead dog and driving it over the cliff to save her Clan. The dog goes tumbling over the gorge, but so does Bluestar. Firestar hurries after his leader, but Bluestar dies shortly after she's pulled out of the river by Fireheart, Stonefur, and Mistyfoot (her own children whom she had sent to RiverClan to save her own Clan and become Clan deputy). Before her death, she tells Fireheart that he is the fire that would save the Clan. Now, after the tearful death of his mentor and leader, Fireheart has no choice but to become leader of ThunderClan. In this book Graystripe also returns to ThunderClan after warning Fireheart when Leopardstar was about to attack him, and pulled her off him.