Ever since the final battle against the Sylphs, Nightpaw hasn’t been able to sleep. No matter how hard she tries to fall asleep, sleep simply will not come to her. There are monsters that haunt her imagination, and bloodstained battles that float around in her mind; even though there’s nothing to worry about anymore – the Sylphs have been annihilated – Nightpaw just can’t forget what she’s done. Over time, every other MoonClan cat will move on and forget the battle, but Nightpaw knows that these memories will haunt her forever.
Nightpaw isn’t used to getting any attention from the cats around her. She can’t even stay inside of camp at night because her memories cause her to cry out and disturb the peace in the MoonClan camp. So when she finds Honeypaw following her out of camp one night, she has to confront him. What he tells her – that he hasn’t been sleeping either – awakens something deep inside of Nightpaw that she never knew existed. Now she knows she’s not the only one.
Nightpaw can’t stop thinking about Honeypaw; she hasn’t seen him since that night, but she still remembers how warm he was against the wind. She can’t stop wondering why he would willingly follow her outside of the camp only to sleep by her side; even though he claims that he also can’t sleep, he fell asleep immediately that night, after all. Even though Nightpaw can’t actually dream – any time she happens to doze off, all she has is nightmares – she can certainly imagine things, and that’s what she does… until Honeypaw jumps off of a cliff, and everything that she thought she knew changes.
Nightpaw knows that Honeypaw is dead now, but she also believes in StarClan. She knows that he’s still alive in some way, up there somewhere, watching her. For the first time ever, she feels completely and utterly alone, even as she goes about her normal business. But while she’s out at night, she sees something stirring deep inside the forest. She chases after it despite her better judgment, and finds Honeypaw – or what’s left of him. But she also finds another spirit cat with him. She hears this new cat tell Honeypaw that he has to destroy MoonClan, or else he’ll destroy Honeypaw. Resisting the urge to run out and confront Honeypaw, Nightpaw instead turns away, knowing that she has to tell someone… but she also knows that she can’t.
Nightpaw now knows that Honeypaw is working with the Sylphs – or, rather, that Honeypaw was half Sylph. It’s a crushing, devastating realization; if Honeypaw, who for all appearances was a normal cat, was actually half Sylph, there could be others, and Nightpaw realizes this. She is also well aware that MoonClan would never believe her even if she told them; they would just dismiss it as the foolish ramblings of a scared little apprentice. However, she feels a desperate need to tell someone, and she starts paying more attention to the cats around her, trying to figure out who’s the most trustworthy. But then Honeypaw visits her one night, and Nightpaw has to second-guess everything she ever thought about him.
Nightpaw has now been crushed even more: she told Rosewhisper Honeypaw’s secret, and Rosewhisper told the whole camp. Now the Clan is bent on tracking Honeypaw’s Sylph self down and destroying him, along with all of the other Sylphs they may find along the way. Now Nightpaw has to stop them, to explain that Honeypaw was never a spy for the Sylphs’ cause. But no one in the Clan will believe her; they even go so far as to throw accusations against her, claiming that she must secretly be a Sylph as well. She has to come up with something, but saving Honeypaw now seems utterly impossible.
Nightpaw managed to save Honeypaw, but now the two of them are on the run from MoonClan; neither can return unless they receive word that their actions have been forgiven, which is unlikely to happen. Together the two former apprentices journey beyond the Clan’s territory, exploring the world, including the land that once belonged to the Sylphs. As they reveal more and more about their ancient adversaries, Nightpaw is finally overtaken by a sense of calmness that she hasn’t felt since the battle.