When she finds the perfect spot in Windemere for her community garden project, Princess Kara gets into an accident while using a flying machine created by her friends, Madison and Makalya. Kara's protective parents warn her that the kingdom is more dangerous than she realizes, a sentiment that is shared by their advisor, Baron von Ravendale. The Baron is considered their most wise and insightful advisor, so the king and queen trust him, but secretly he wants to take over the kingdom. He first aims to create an elixir to give him super powers, which will help him achieve his goal.
The Baron makes his frog Bruce track down ingredients for the potion while he does his usual activities. Kara herself gains super powers when she is kissed by a magical butterfly. She discovers her powers the next day, and she tells Madison and Makalya about it. Kara finds out that she can fly, has super strength, improved agility, and she realises that it was the butterfly who gave her powers. Madison and Makalya tell Kara she can only use her powers to help others, not for personal gain.
While Kara would like to start her community garden project, she knows her parents woul disprove. She assumes a superheroine alter-ego named Super Sparkle, and her friends design her a costume. At a construction site, Super Sparkle rescues her cousin Corinne, a construction worker, and reporter Wes Rivers from being hurt. She then realizes that she forget about a royal reception, and rushes back. The Baron sees Super Sparke in action and wonders how she got her powers, but focuses on getting the remaining ingredients that he needs.
Back in her bedroom, Kara tells Madison and Makalya that she could rescue people and capture criminals with her powers. They reveal that they have created a secret base to help her find emergencies. Kara prevents a robbery and the Baron finds the last ingredient for the elixir. Kara's sisters Zooey and Gabby tell her that they would like to meet Super Sparkle, and suggest inviting her to Kara's birthday party next week. Kara goes to save someone from a fire, and takes a photo with Wes, who has done a lot of reporting on her since she began being a superheroine.
On her birthday, Kara sees that she has many fansites and a tribute music video. At the party, Kara's cousin Corinne says she thinks Super Sparkle is overrated, but the king and queen express gratitude towards Super Sparkle helping people in the kingdom. Kara leaves to stop another robbery, and Madison and Makalya distract her parents until she gets back. Without realizing, Kara drops her ring, which Madison and Makalya created to have superhero tools.
Corinne sees Super Sparkle change back to Kara, making her the only person besides Madison and Makalya to know Super Sparkle's real identity. She overhears them say that the butterfly gave Kara powers, so Corinne tracks the butterfly down and receives a kiss. She gets super powers and creates a superheroine alter-ego named Dark Sparkle. Wes finds Kara's ring, and the Baron finds his last ingredient. Super Sparkle and Dark Sparkle meet and become rivals.
Wes sees photos of Kara and Super Sparkle wearing the same ring, so he exposes her identity on his blog. Her parents forbid her from acting as Super Sparkle, and the Baron doubles the ingredients to intensify his potion's powers. He says to Bruce that he will rid the realm of its King and put an end to Super Sparkle and Dark Sparkle. He drinks the elixir, finally gets super powers, and tries to attack the king. Corinne uses her powers to save him, so her family finds out she is Dark Sparkle.
Kara's pets, Parker and Newton, try to help stop the Baron, and find the butterfly, so they get super powers too. The Baron tries to attack Kara's family at a stronghold they are in for protection, but it can withstand any assault. He goes to Mount Dormant, a volcano, and causes lava to flow towards Windemere. Dark Sparkle helps Super Sparkle to divert the lava to a lake. Parker and Newton help Dark Sparkle and Super Sparkle to stop Bruce and the Baron, and imprison them in the stronghold. Kara and Corinne decide to work together to make Windemere a better place, and Kara begins her community garden.
