Crysta was a student of Magi Lune, the elder fairy who taught her magic. Crysta's blue streak that appears when she flies is a result of her growing magical abilities. Crysta is a bit flakey when it comes to her lessons, skipping one of Magi's lectures to hang out with her friend Pips.
One day, Crysta flies above the canopy and sees smoke on the horizon. Curious, she flies toward it accompanied by a bat named Batty Koda. When she gets there, she sees a machine called the leveller which is tearing down the trees. She runs into a human called Zack and shinks him down in a moment of panic.
Crysta asks him about the machine that was tearing down the trees and he denies any involvement. Crysta offers to take Zack to Fern Gully to meet the other fairies, as none of them have seen a human before. Crysta then takes Zack to an underwater lagoon and the two share a romantic moment. Crysta then searches for Magi and asks her to meet Zack. Magi subtly tells her that Zack and several other humans have destroyed most of the rainforest, as a result Hexxus-the spirit of pollution-has resurfaced and is making his way towards Fern Gully.
Magi then unites all the fairies together and they draw on the latent magic of the rainforest to strengthen themselves. Magi loses her physical form in the process but leaves Crysta with a magic-infused seed. Just then, Hexxus arrives. Hexxus has commandeered the leveller and plows his way through Fern Gully. Zack, Crysta, Batty and Pips all stand up to Hexxus nad are nearly killed, until Zack manages to switch off the leveller's engine. Hexxus seemingly fades away, only to come back in a more terrifying form.
Crysta flies straight into Hexxus' open mouth, planting Magi's seed within him and causing a tree to grow from the inside-out. The other fairies use their new-found magical abilities to help the tree grow, entombing Hexxus within. Crysta is reborn from a flower, her power now fully awakened. She gives Zack a heartfelt farewell and grows him back to normal size. Crysta then sets about regrowing the rainforest.