Plot
A magical realm is divided between the Fairy Kingdom and the Dark Forest. When fairy princess Marianne sees her fiancé, Roland, kissing another fairy on their wedding day, she vows never to fall in love again. In the Dark Forest, the Bog King has the same view on love, despite his caring mother Griselda's protests.
Marianne's sister, Dawn, and her elf friend, Sunny, are nearly devoured by a giant lizard before Marianne rescues them. After falling through the border and into the Dark Forest, Sunny finds a primrose petal and hides it. At the Spring Ball, Roland tries to win back Marianne, who angrily drives him away. Roland consults his warriors, who jokingly tell him to procure a love potion to woo Marianne. Roland then encounters Sunny, who has an unrequited love for Dawn, and convinces him to venture into the Dark Forest to get the love potion so they can use it on their respective fairies. Sunny goes back and finds the hidden primrose petal and, with the guidance of an Imp, travels to the Bog King's lair, where the Sugar Plum Fairy was being held prisoner by the Bog King. Sunny finds the Sugar Plum Fairy, who agrees to make the love potion if Sunny promises to set her free.
Plum's escape rouses Bog King, who recaptures her while Sunny and the Imp escape. Sunny returns to the ball and tries to hit Dawn with the love potion. Bog interrupts the celebrations and captures Dawn just as she is sprayed by the love potion and the imp steals it in order to spread it throughout the forest. Bog orders them to deliver the potion to him by moon-down or he will harm Dawn. Defying her father's order, Marianne flies off after her sister while he grants Roland a small army to head off on foot to Bog's castle.
Dawn falls in love with Bog due to the potion, and Bog has her imprisoned for his own sanity. Marianne arrives and fights with Bog to return her sister. When she realizes the severity of the situation, the two of them begin to find common interests. When they consult Sugar Plum for an antidote, she explains that true love will negate the effects of the potion. Bog hadn't known this, as he refused to listen to Sugar Plum after his failed attempt with the love potion years before. A mutual attraction begins to develop between Marianne and Bog, but only Griselda sees it.
Sunny recovers the potion from the imp and gives it to Roland as they march on to the castle. Bog sees this and suspects that Marianne had set him up, breaking his heart again as he leaves her stranded in a spider web. She escapes and joins in the battle taking place at the castle. Sunny frees Sugar Plum, Dawn, and the love-stricken forest creatures that the imp had hit with the love potion.
In the escape, Bog holds the mouth of his den open long enough for everyone to escape. He survives, to Marianne's relief, and Sunny reveals his true feelings to Dawn. After realizing her love for Sunny, the spell of the love potion breaks, and the two kiss. Roland returns after appearing to fall to his death, love potion in hand. He sprays Marianne, much to the dismay of Bog, and she appears to be under the spell and begins singing. Sugar Plum holds a very outraged Bog back and urges him to wait and watch. While going in for a kiss, Marianne punches Roland, who falls into the crevice after being sprayed with the falling love potion. It is revealed that the potion didn't work on Marianne because she is already in love with someone else. Bog and Marianne finally admit their feelings for each other and kiss.
In a post-credits scene, Roland returns to his warriors and has fallen madly in love with a female insect who Griselda had presented to Bog as a potential wife earlier in the movie, much to his warriors’ disgust.