The story opens with a car speeding away, and a frantic kittypet chasing after it.We see that one of the Twolegs in the car is an elderly man, and he shows his companions a photo, explaining that he and his late wife owned a cat, but that they aren't allowed to have pets at the nursing home he's on his way to.The kittypet stops, exhausted. Her name is Sasha, and she feels lost. She grew up owned by elderly Twolegs named Ken and Jean, and she loved her life: during the day she'd stay with them, and at night she'd explore outside. Then Jean grew ill, and eventually died, so it was only Sasha and Ken. Lately, however, Ken had been getting ill as well, and this morning he left with strange Twolegs, locking Sasha inside the house (she got out through a window). Sasha decides to wait by the house for him. In the evening, a neighbor, who is meant to take care of Sasha now, comes to feed her, but Sasha does not arrive. She stays outside all night, still waiting, finally realizing when the sun comes up that Ken probably isn't coming back.She briefly meets with a kittypet friend, Shnuky, and explains the situation to her. Then she heads into the forest. Over the next few days, she settles into a den in a pile of logs, and is able to hunt for herself. One morning, she meets a rogue tom named Pine. He helps pull off her collar, and explains the difference between rogues, kittypets, and Clan cats. He shows her some scars from a fight with Clan cats, and warns her to stay away from them.Sasha is curious about these Clan cats, and the next morning a ShadowClan patrol containing Tigerstar, Rowanpaw, and Jaggedtooth happens to stop shortly underneath the tree she's hiding in. The same patrol passes through again the next day. Rowanpaw nearly misses a frog, which Sasha catches and gives to the patrol. Tigerstar speaks to her alone shortly, introducing himself and warning her away. The next night, Sasha is hunting alone, and nearly misses a rabbit, which Tigerstar catches. They get to talking, and start meeting nightly. Sasha begins to fall in love with him.He eventually finds her den, and her collar, and insists that she bury it and put her kittypet life behind her, leaving in disgust. She doesn't see him again until one day she gets attacked by two foxes. Tigerstar rushes in and the two of them drive the foxes away. Tigerstar is injured, however, and she invites him to spend the night in her den to recover. They continue to meet, and she decides to show him her kittypet home. He's quite uninterested in it, but he decides to show her his home - the ShadowClan camp. Sasha stays with the Clan for a day, quickly getting comfortable with lifestyle of a Clan cat.On patrol, they run into trespassing ThunderClan warriors. The ThunderClanners call Tigerstar "traitor", so Tigerstar explains to Sasha about how he was driven out of ThunderClan because Bluestar was envious of his strength, and how he now fears that Firestar wants to rule the whole forest. As Sasha prepares to leave to go back to her den, Tigerstar asks her if she wants to join ShadowClan. She decides to think about it for a day. After an encounter with Pine, who is not looking too healthy, she makes her decision: she will join the Clan. On the way to the camp, she comes upon a meeting of warriors, with Tigerstar. She doesn't feel like interrupting, so she waits in the bushes, listening curiously. She hears him telling his senior warriors that Scourge has agreed to support him, and that taking over RiverClan is the next step. He'll use a pack of dogs to destroy ThunderClan, and then he'll be free to rule the forest.Sasha runs away in panic. Tigerstar lied to her - he's the real enemy of the forest. She arrives at her den, forgetting that she'd planned to meet him the next day once she's made her decision. He comes along, expecting an answer: will she join ShadowClan?