Charlie Plummer (right) and Taylor Russell appear in a scene from "Words on Bathroom Walls."

“Words on the Bathroom Walls” is a sincere misfire.

Based on a novel by Julia Walton, it is a film that is trying to say something about teenagers that deal with mental illness but the message gets lost because of a weird tone that can’t decide how it wants to present the message.

In “Bathroom Walls” Charlie Plummer stars as Adam, a soon to be senior who dreams of going to culinary school to become a chef but is battling personal demons – specifically schizophrenia.

When he is expelled from a public school after an incident, his mother (Molly Parker) sends him to a Catholic School to finish out his senior year. Adam just wants to lay low, keep his illness a secret and fit in, but he meets a student named Maya (Taylor Russell) and there is an instant attraction.

As their romance deepens, he becomes more and more guarded about his illness. And just when it looks like he has the illness under control, things spiral out of control – leaving Adam with no one to turn to.

“Bathroom Walls” is at its best when the focus is on the relationship between Adam and Maya. Plummer and Russell (who many might remember from last year’s wonderful little film “Waves”) have great chemistry that really makes it easy for the audience to invest in their journey.

Unfortunately, their relationship is overshadowed by Adam’s personal demons – which are handled with kid gloves in the film. It’s a movie that makes the wrong decision of trying to depict the chaos inside Adam’s head by having AnnaSophia Robb, Devon Bostick, and Lobo Sebastian play three distinct characters he battles with in his head. It’s a gimmick that never really works, feeling like it was borrowed from Disney’s “Inside Out.”

This feels like something that would have played better in a book than a feature film, creating some awkward shifts in tone that undermine what “Bathroom Walls” is trying to say. Parker, Walton Goggins and Andy Garcia try to add some depth to the material but it never hits the right notes.

By the time it builds to a rather cringe-worthy finale, it is clear that director Thor Freudenthal and screenwriter Nick Naveda have earnestly tried to create a family film that deals openly with mental illness but they just failed to hit the mark.

Starring: Charlie Plummer, Taylor Russell

Directed by: Thor Freudenthal

Rating: PG-13 for mature thematic content involving mental illness, some sexual references, strong language and smoking

Playing at: Regal Bowling Green Stadium 12, Highland Cinemas (Glasgow)

Grade: C