Gilroy, known for his Oscar-nominated "Michael Clayton" and the critically acclaimed series "Andor," immerses viewers in the life of Alex Serian, a cellist portrayed with subtle conviction by Pedro Pascal. Serian's existence is deeply intertwined with music, a legacy passed down through generations of his family, from his session musician grandfather to his composer father and musically accomplished mother and brother.
The film, distributed by Searchlight and slated for a December 4, 2026 release, is described by Deadline as a poignant love letter to the often-unsung heroes of Hollywood's soundstages. It explores how the relentless pursuit of professional musical careers has shaped—and sometimes strained—the Serian family's personal lives. Alex, a nomadic cellist drifting through cities and relationships, finds himself at a pivotal moment, returning to Los Angeles after two decades. He grapples with his mother's declining health, his brother's eccentricities, and a lingering mystery surrounding a 15-year-old pop prodigy, Viviana Glenn, who might hold a significant secret from his past.
"Behemoth!" unfolds in a non-linear fashion, expertly weaving together present-day scenes of Alex working on movie scores with flashbacks to his earlier romantic entanglements and professional journeys. Key encounters include a humorous confrontation with an ex-lover, Carol Spedding (Olivia Wilde), and a complex relationship with fellow musician Nadia Hynes (Eva Victor), whose tragic death leads Alex to question his connection to Viviana.
A standout element of the film is its innovative musical score. Instead of a single composer, Gilroy enlisted "The Behemoth! Collective," a group of nine renowned maestros including Michael Giacchino, James Newton Howard, and Alan Silvestri. Deadline hails the collective's work as "hands down the year’s best," creating a rich tapestry of sound that guides Alex's emotional maze. The film also features a memorable original song, "Your God Is Sleeping," performed by the fictional Viviana.
Pascal's portrayal of Alex is lauded for its understated depth, with Deadline noting he "subtly plays Alex in a low-key style with no showboating or anything that rings false." The ensemble cast also delivers strong performances, with Alexa Swinton shining as Viviana, Jo Beth Williams offering poignant moments as Alex's mother, and Hank Azaria impressing as his father through a discovered video letter. Olivia Wilde and Will Arnett provide lighter, balancing touches.
Ultimately, "Behemoth!" transcends a mere character study to become "a gorgeous and glorious tribute to those who make the music that help make movies like this one so much richer," as observed by Deadline. It celebrates the artistry behind film scores while exploring themes of legacy, identity, and the search for belonging.