Isla is a girl who despises magic and considers magic users an abomination, though it is unknown why. One day, while Isla, Seraphina and their friends are trying on dresses, Gothel, a tree nymph, causes a flower on one of the dresses to bloom. When they re-enter the room, Isla and Seraphina insist that they are fine with her having magic and invite her to a ball tonight; she agrees to come and teach them magic.
That evening, Isla takes Seraphina, Gothel and the others to an abandoned greenhouse, as Seraphina worries about the consequences of what will happen if Gothel uses her magic in public. When Gothel magically makes a flower grow, Isla betrays her by stepping on the flower and having the others hold Gothel as she dumps mud on her and steals her key. After taunting Gothel, Isla leaves with the others, though Seraphina sadly looks at Gothel before following the others. Using Gothel's key, Isla manages to access the Tree Nymphs' grove, where she kills all of the tree nymphs using axes and torches.
After finding out what Isla had done, Gothel returns to the ball to kill her. Not taking Gothel seriously, Isla attempts to have two guards capture her, only for her to impale them with roots, shocking Isla. As Isla and Seraphina back away from Gothel, the guests attempt to flee, only for Gothel to lock the door with roots. She then uses them to tie Isla up and, as she begs for her life, snaps her neck, which kills her.
Isla's actions would prove to have dire consequences, as it leads Gothel to eradicate all of humanity except Seraphina, who turns out to have magic. Once humans return, Gothel would later attempt to eradicate them again, only to be turned into a tree by her daughter.