At first I wasn’t sure if Neverlake was going to be a GU movie – there isn’t a definite adversary until later in the plot – but the first hint was the large number of Peter Pan references throughout (the title of course, the collection of strange children led by a boy named Peter, the protagonist’s mother having the last name Darling, etc.).
Jenny never knew her mother, and her father put her in boarding schools until one day he invites her to live with him in Italy. She meets a bunch of creepy children in an old institution who tell her there are ancient souls trapped in the nearby lake because their sacred statues had been stolen (Jenny’s father is an Etruscan scholar who has many of these statues in his house). They show her how to save those souls, and eventually she must save the children, too. Eventually, Jenny’s own father is revealed as the adversary in a quite horrific way – I have to wonder if this is a nod to the Peter Pan stage tradition of having Wendy’s father also play Captain Hook – and she must fight him. She also discovers her long lost mother, so there’s the GU trope of rescuing a family member. Hard to say much more without entirely spoiling the plot, but this was a surprisingly original movie (you’d never guess from the ridiculous cover and tagline) and rather disturbing as well.