In the series, Buffy Summers is a teenager who, at the age of fifteen, was chosen by mystical forces to be the latest "Slayer", a girl endowed with superhuman powers to fight and defeat vampires, demons, and other evil forces. After moving with her mother, Joyce (Kristine Sutherland), to the fictional town of Sunnydale, she befriends Willow Rosenberg (Alyson Hannigan) and Xander Harris (Nicholas Brendon), who join her in the struggle against evil. They are guided by Buffy's "Watcher", Rupert Giles (Anthony Stewart Head), who is well-versed in demonology and is responsible for Buffy's training as a Slayer. The group collectively refer to themselves as the Scooby Gang. During season two, Willow begins to experiment with magic, eventually becoming a formidable witch.