The nature-talent fairies are bringing to the mainland the season of leaves, hibernation, chilly breezes, and pumpkins: autumn. Meanwhile, Tinker Bell and dust-talent fairies like Terence are staying in Pixie Hollow. Tinker Bell is trying to make a "Pixie Express", but it fails just as she is called to meet Queen Clarion, Fairy Mary and Redleaf, the Minister of Autumn.
They show her a mystical moonstone and explain to her its tremendous powers. Every eight years, there is a blue harvest moon in Pixie Hollow. When the light of this rare blue moon passes through the moonstone, it creates blue pixie dust to strengthen and rejuvenate the Pixie Dust Tree. The Autumn Revelry is the associated event during which the fairies gather to collect the dust.
A new scepter is to be made to raise the moonstone, and Tinker Bell has been recommended. Although Tinker Bell made mistakes in the past, Fairy Mary explains that tinker fairies learn from them most of the time. Tinker Bell accepts the task, as well as help from Terence. But as the work on the scepter progresses, Tinker Bell begins to have trouble with Terence, who is trying too hard to be helpful. When Terence accidentally breaks the scepter, Tink becomes furious, causing her to break the moonstone, which is to go into the scepter. That evening, she attends a fairy tale theatre show about the Mirror of Incanta, a magic mirror which granted two of three magic wishes before becoming lost. Tinker Bell sets out in a balloon she creates to find the Mirror of Incanta. Tinker Bell intends to use the third and last wish to restore the shattered moonstone to its original form.
While trying to evade a hungry bat, a firefly named Blaze crash-lands into Tinker Bell's balloon, though the pixie fails to notice. After flying further, Tinker Bell begins to get hungry but when she looks through her food pouches, she finds that the food has all been eaten by a firefly. Tink orders the firefly to leave, which he seemingly does, though he truly wants to tag along with Tink on her quest to find the magical mirror that can grant one wish. Tink hopes to use the wish to repair the shattered moonstone that will provide blue pixie dust for the fairies. After Blaze's apparent exit, Tink tries to read her map, but it is too dark to see. Blaze then sheds light on the map to help Tink, and she finally allows him to stay. As the duo's adventure continues, Tink thinks she has stumbled upon the stone arch that is said to lead way to the mirror. She leaves the balloon to make sure of this, and leaves Blaze to watch over things. While Tink is out however, the balloon begins to stray away, and Blaze rushes to tell Tink. Tink is too busy trying to figure out why she stumbled upon a bent tree instead of the stone arch to notice Blaze. When she finally sees the balloon floating off, she briefly blames Blaze. The two follow after it, but the harsh winds knock them down. The next morning, Tinker Bell awakens and is hungry and lost.
Blaze scouts out to rally some forest insects that provided food and water for Tink. They also lead her and Blaze to the stone arch, and the adventure continues. They find the shipwreck that is said to house the mirror and head inside. Tinker Bell finally discovers the mirror, but she accidentally wastes the third wish, wishing Blaze to be quiet for one minute. She gets furious at Blaze and blames him, but she begins to cry. She is found by Terence, who followed her after discovering her plans and the fragments of the moonstone in her empty house. They get chased by rats and run back to the balloon.
Tinker Bell and Terence start back to Pixie Hollow. Along the way, Tinker Bell fixes the scepter using a white gem from the top of the mirror, the scepter pieces Terence has wisely brought, and the moonstone pieces, all set at just the right angle. She discovers the magic of true friendship, humility, and love. Thanks to inspired teamwork with Terence, she is ready to give the scepter to Queen Clarion.
When she unveils the scepter, the assembled fairies are all shocked and alarmed to see the fragments of the precious moonstone. However, the broken moonstone shards create an unexpected benefit: they drastically magnify and increase the surface area through which the rays of the blue moon can pass, creating the largest supply of blue pixie dust ever seen in Pixie Hollow.
The voice actors are largely the same as in the previous film. America Ferrera did not return to voice Fawn and was replaced by newcomer Angela Bartys.
- Mae Whitman as Tinker Bell, a tinker fairy
- Jesse McCartney as Terence, a dust-keeper fairy
- Jane Horrocks as Fairy Mary, the overseer of the tinker fairies
- Lucy Liu as Silvermist, a water fairy
- Raven-Symoné as Iridessa, a light fairy
- Kristin Chenoweth as Rosetta, a garden fairy
- Angela Bartys as Fawn, an animal fairy
- Rob Paulsen as Bobble, a wispy tinker fairy with large glasses / Grimsley, a tall troll / Mr. Owl
- Jeff Bennett as Clank, a large tinker fairy with a booming voice / Fairy Gary, the overseer of the pixie-dust keepers / Leech, a short troll
- Grey DeLisle as Lyria, a storytelling fairy / Viola, a summoning fairy / Narrator
- John DiMaggio as Redleaf, the Minister of Autumn
- Eliza Pollack Zebert as Blaze, a firefly
- Bob Bergen as Bugs / Creatures
- Roger Craig Smith as Bolt, a pixie-dust keeper / Stone, a pixie-dust keeper
- Allison Roth as French Fairy
- Thom Adcox-Hernandez as Flint, a pixie-dust keeper
- Anjelica Huston as Queen Clarion, the queen of Pixie Hollow