Bluestar gives the two apprentices, Firepawand Graypaw, their warrior names, Fireheart and Graystripe. The book begins where the first book ended, with the two new warriors finishing their nighttime vigil. Bluestar then assigns the two warriors with the task of bringing WindClan (who were forced out of their home by Brokenstar, the former ShadowClan leader) back to their original home. They find WindClan far past HighStones and in a tunnel under a tangle of Thunderpaths. They find the tunnel, and spot Twolegs. The two warriors run into WindClan, and convince them to come home. On their way back from their successful mission accompanied by a WindClan escort, they decide to take a short cut by the gorge in RiverClan territory. They are caught by a RiverClan patrol, which forces them into a fight. A ThunderClan patrol arrives to help their fellow Clan mates. Graystripe is engaged in battle with Whiteclaw, a RiverClan warrior near the gorge. Graystripe nearly tumbles off the cliff, while his opponent Whiteclaw gets the worst of it and falls into the roaring river below, drowning. Fireheart saves Sandpaw from falling off the cliff.Graystripe, Fireheart's best friend, falls into the river one day and almost drowns. Silverstream, a RiverClan cat and the daughter of Crookedstar, saves his life. Later, Graystripe falls in love with the silver cat. Fireheart knows Graystripe is breaking every rule of the warrior code by falling in love with Silverstream, but he still covers for him. Fireheart tries to discourage them from seeing each other, but it doesn't work. Graystripe finally says that he will only meet her at Gatherings, but later on in the book, Fireheart realizes Graystripe has been seeing her secretly again. Fireheart also trains his apprentice, Cinderpaw, and Graystripe's apprentice, Brackenpaw. But then Cinderpaw goes to get a message to Tigerclaw, and is injured on the Thunderpath (a road [the "message" was supposed to kill Bluestar so he could become leader of ThunderClan]) A fight with WindClan against RiverClan and ShadowClan tests Fireheart's and Graystripe's loyalty to their Clan. Graystripe attacks only the ShadowClan warriors, and it is very clear that his loyalties have been divided. Silverstream attacks Fireheart thinking he is someone else. She lets him go when Graystripe cries "Silverstream! No!", but Fireheart instinctively pins her down afterward. He only lets her go when he sees a horrified-looking Graystripe. Unfortunately, Darkstripe sees him, and later tells Tigerclaw. At one point in the battle, Fireheart gets attacked by Leopardfur. Tigerclaw stood nearby, but did nothing except watch while Leopardfur prepares to kill Fireheart. Fireheart is certain now that Tigerclaw can never be trusted (with good reason to). Also, Fireheart is reunited with his sister, Princess, a kittypet living in Twoleg place early in the book. After Cinderpaw is crippled by her Thunderpath accident, Princess gives Fireheart her oldest kit, Cloudkit, to take into the Clan so that her brother can have another apprentice. Fireheart agrees to take the kit, but the rest of the Clan are reluctant to accept him because of his kittypet blood. The only cat to give Fireheart support is Graystripe, even though they didn't seem to be great friends at the time. Even so, Bluestar names Fireheart's nephew Cloudkit (without a naming ceremony) and allows him to stay, and Brindleface becomes his "foster mother." At the end of the book, Fireheart tells Graystripe that his relationship with Silverstream is his own thing to work out and that he won't try to interfere with it anymore, and their friendship seems to be back to normal again.