The Forgotten Warrior begins with Jayfeather waking up from a nightmare. He remembers that Lionblaze told him about how Briarlight snuck out with Bumblestripe and was almost eaten by dogs, Lionblaze saving them without getting hurt. Briarlight tells Jayfeather how she found a tuft of black fur in the back of the herb store, and Jayfeather recognizes it as Hollyleaf's. While Dovewing and Ivypool are on patrol, Dovewing fears that she lost her special power, being unable to hear, see, or smell farther than an ordinary cat. Birchfall reveals to Ivypool that he is training in the Dark Forest, to Ivypool's horror, though she hides it. On the way back, a WindClan patrol accuses them for washing their paws in the river, believing the river to be WindClan territory. Sorreltail stops them before there is a fight. When chasing a squirrel, Dovewing almost passes the ShadowClan border. Tigerheart spots her and tells Dovewing that his sister Dawnpelt wants to take revenge on ThunderClan because she suspects that Jayfeather killed her brother Flametail. Later, Molekit and Cherrykit become apprentices. Brackenfur tells the Clan that Sorreltail will be having kits. Dovewing confesses to Lionblaze that she is afraid that she had lost her powers. Lionblaze comforts her but he feels nervous. WindClan accuses ThunderClan of crossing the border. They deny it but WindClan is jumpy. Later, Molepaw and Cherrypaw enter camp with their mentors announcing that they were attacked by foxes. They tell them how a stranger scared the fox off before any serious injuries were inflicted. The rest of the Clan thinks that the new apprentices are making it up, but Jayfeather and Lionblaze thinks that it might be Hollyleaf. Lionblaze convinces Firestar to let him track down the stranger so he does. He discovers Sol and brings him back to camp. Bumblestripe is in love with Dovewing and the two go on a midnight walk. Her power finally comes back during this walk, much to Dovewing's delight. Afterward, her and Bumblestripe start getting closer to one another. In a dream, Yellowfang tells Jayfeather to tell Cinderheart about her past so she can help the Clan with her medicine cat abilities.. He refuses but tells Cinderheart later anyway. While on a walk, Dovewing and Ivypool go into the tunnels underground. They hear Sol discussing an attack on ThunderClan with WindClan. Dovewing and Ivypool are overheard by the cats and they try to escape. They find Hollyleaf and she helps them get out. Lionblaze sees her and brings her back to the Clan. Hollyleaf reveals that she killed Ashfur with Brambleclaw's support. Brambleclaw lies to the Clan, saying Ashfur's death was an accident. Hollyleaf also tells everyone that she saved the apprentices from the fox attack, not Sol. Everyone welcomes her except for only a few. Sorreltail goes on a walk and gives birth outside of the hollow and names her kits Lilykit and Seedkit. Cinderheart is now convinced that she should be a medicine cat, revealing to the Clan that she is Cinderpelt reborn. Yellowfang is mad at Jayfeather for telling Cinderheart her past, but Jayfeather tells her that it was not his idea. Yellowfang becomes nervous, saying she made a mistake about telling Cinderheart. Hollyleaf begins tunnel training to help with the fight with WindClan. Ivypool is still visiting the Dark Forest at nights. When she tells Brokenstar that she wants to teach the cats, he tells her to kill Antpelt again. Ivypool wins and kills Antpelt, who fades and disappears, showing how that the Dark Forest cats can be killed. In the end, ThunderClan wins the battle with WindClan by pushing them into the tunnels. After, Dovewing and Hollyleaf go back to ThunderClan.