On her sixteenth birthday, Sabrina Spellman finds out that she is a witch. However, instead of helping her, it actually makes life more difficult, especially after she gets on the wrong side of head cheerleader, Libby.

In order to find out what Libby has been saying about her and Jenny, Sabrina gives her a piece of cake covered with truth sprinkles. However, when her teacher shares the cake with students and teachers, Sabrina finds that the truth hurts.

Sabrina tires of Libby's constant teasing-- which worsens when Sabrina joins a science club-- so she gives the tormentor a taste of the taunting by turning her into a nerd. Meanwhile, Zelda wants Hilda to throw out some very old items. Tired of watching Libby treat people badly, Sabrina decides to give Libby a taste of her own medicine by transforming her into a geek. However, when Libby succeeds in turning her fellow geeks against the entire school, Sabrina must find a way to unite her classmates before the plan backfires.

Hoping to encourage more students to join the Adopt-A-Grandparent program, Sabrina finds a mischievous way to get trend-setting Libby to participate: she impersonates her, necessitating quick Superman-style telephone booth transformation whenever the real Libby turns up. But Sabrina's well-meant scheme goes wrong when Libby bonds with Sabrina's adopted grandmother Nana, who claims to know most of Hollywood's young hunks personally. Meanwhile, Zelda can't decide whether to continue dating a man who is centuries younger than she is; and Hilda and Salem eat too much of a magical "hair soup" that causes their hair to grow at an exponential rate.

Sabrina's fears become reality when she takes part in a re-creation of the Salem witch trials and is accused of sorcery while defending Jenny's honor. Libby made up a bunch of lies, just to get rid of Sabrina and Jenny, accusing them of practice witchcraft. At the end, all teachers realizes that she was lying, and Sabrina casted a spell on her as a revenge.

After Sabrina's room turns into a circus tent, she must walk up and down the tightrope until she finds a balance in life between boyfriend, friends and her job.