120-Minute Drama 'Mouse' Explores Teen Grief Through Theatre and Friendship

Screenwriter and director Kelly O’Sullivan has released a new feature film titled Mouse, which centers on the quiet resilience of a high school student named Minnie. The 120 minute drama, rated NR for its 2026 theatrical run, examines how young people process loss when their social support systems collapse. The narrative structure relies heavily on theatrical exercises rather than plot twists, using the stage as a mirror for internal change.

The story opens in a theatre class where teacher David Hyde Pierce guides students through improvisatory prompts. He asks them to physically embody their public selves, and most students expand their bodies to take up more space. Minnie, played by Katherine Mallen Kupferer, does the opposite. She curls inward, occupying less room. When the prompt shifts to their private selves, the class shrinks again, but Minnie lights up. This contrast establishes her central conflict: she is invisible in public but vibrant in private, a dynamic that defines her relationships throughout the film.

Minnie’s life is dominated by her best friend Callie, portrayed by Chloe Coleman. Callie is charismatic and popular, with big ambitions to attend Juilliard. Her mother, Sophie Okonedo, a former concert pianist, actively nurtures these dreams. The disparity between the two girls is sharp. Minnie is sharp-witted but struggles to be heard, while Callie moves with ease through a group of affluent peers. During a slumber party, a mean girl in the group initiates a game called playing personal feedback. She tells Minnie, with a fake smile, that she always kind of forgets she exists.

The friendship is tested by an accident that occurs before the students’ senior year. This event forces Minnie to redefine herself without Callie by her side. O’Sullivan, who co-wrote and co-directed the film with Alex Thompson, focuses on the cellular connection between the two friends. The writing captures not only the cruelty of teen dynamics but also the deep love that persists despite their differences. The loss is painful precisely because the bond was so strong.

The film avoids the conventions of a traditional hangout movie. The atmosphere is not light or fun, but it is accompanied by a sense of compassion and unhurried energy. The drama is built on the routine aspects of life, such as going to work, attending school, and thinking about dinner. These mundane tasks continue even during terrible loss. The filmmakers rely on relatable human moments rather than histrionics, suggesting that everyday life is a valid subject for cinema.

Mouse shares thematic ground with Ghostlight, the previous collaboration between O’Sullivan and Thompson. Both films deal with the grief of those left behind and the role theatre plays in rebuilding a person. They both build toward a third act performance, though the effect differs between the two movies. The cast includes Katherine Mallen Kupferer, who is believably awkward yet glints with a confident coolness. Her real-life mother, stage veteran Tara Mallen, plays Minnie’s single mother. The duo also played mother and daughter in Ghostlight, although that film focused on the father, Keith Kupferer.

Sophie Okonedo delivers a complex performance as Callie’s mother. She portrays a character who appears perfect at first glance but gradually comes undone. Her performance ranges from stunned pain to caustic humor. The film grants grace even to the mean girl, creating a tone that is funny and full of compassion. The result is described as a feel-good grief movie, a rare combination in recent cinema. The film is set for release in 2026 and features Iman Vellani and David Hyde Pierce in supporting roles.