First Series

The original series, released from 2003 to 2004, consists of six books: Into the Wild, Fire and Ice, Forest of Secrets, Rising Storm, A Dangerous Path, and The Darkest Hour. The series follows a pet cat, or "kittypet", named Rusty who has had dreams about the forest that lies beyond the neighborhood he lives in. He discovers the dreams are from StarClan, the spirits of the ancestors of the wild cats in the forest, later in the series. One day, he ventures into the forest and is invited to join ThunderClan, one of the four groups of wild cats living in the forest. He accepts the invitation, and receives the name Firepaw. Later, Firepaw receives his warrior name, Fireheart, and discovers that Tigerclaw, the deputy of ThunderClan, wishes to kill Bluestar in order to succeed her and become leader himself.
In the third book, Forest of Secrets, Fireheart becomes deputy of the Clan after Tigerclaw tries to kill Bluestar and fails: he is banished from the Clan. Bluestar eventually dies in A Dangerous Path, sacrificing her life to protect the Clan from dogs sent by Tigerstar, who is now the leader of ShadowClan. Fireheart then becomes the leader, receiving his nine lives and new name, Firestar.
Tigerstar then, in The Darkest Hour, attempts to take over all four Clans, telling them that the leaders will rule together. Leopardstar, leader of RiverClan, agrees, but Firestar and Tallstar, the leader of WindClan, refuse. Tigerstar then tries to use BloodClan to take over the Clans, but Scourge kills Tigerstar and decides to take over the forest for himself. The four Clans unite, and fight against BloodClan. Firestar kills Scourge during the battle, losing his own first life as well, thus defeating BloodClan and saving the forest.