Insidious: The Last Key (2018)

Last updated:
October 9, 2025

Insidious: The Last Key (2018) is the fourth installment in the Insidious franchise and serves as a prequel to the first two films. Directed by Adam Robitel and written by Leigh Whannell (who also appears in the movie), it dives deeper into the backstory of psychic Elise Rainier, exploring her traumatic childhood and the origins of her connection to the spirit world.

Table of Contents

Detailed Summary

Childhood in Five Keys

The film begins in 1953, in Five Keys, New Mexico—an ominous name that foreshadows the movie’s central motif. A young Elise lives with her parents and younger brother, Christian, in a house near a prison. Elise can see ghosts, a gift that horrifies her abusive father, Gerald, who beats her in an attempt to “cure” her. One night, Elise opens a mysterious red door in the basement after hearing ghostly whispers—and inadvertently releases a powerful demon into the world. Soon after, her mother Audrey is murdered by this entity.

The Call Back Home

Decades later, Elise (now an experienced paranormal investigator, played by Lin Shaye) is living in California. She receives a call from a man claiming his house is haunted—the same house she grew up in. Despite her hesitation, Elise decides to return, accompanied by her loyal sidekicks Specs (Leigh Whannell) and Tucker (Angus Sampson).

The Haunting Begins Again

Back in her childhood home, Elise confronts her buried memories. The haunting quickly becomes personal—she finds evidence that her father had kept a woman imprisoned in the basement. But the twist comes when Elise realizes that some of the “ghosts” she’s seeing aren’t dead—they’re victims trapped by her father’s cruelty. This revelation shifts the film from pure supernatural horror to psychological trauma.

The Demon Revealed: Keyface

The malevolent entity Elise released as a child finally reveals itself as “Keyface,” a demonic creature with fingers shaped like keys. Each key can lock away parts of a person’s soul—literally silencing victims by turning off their voices. Keyface has been feeding off the fear and suffering that originated in this house for decades.

Elise also reconnects with her estranged brother Christian and meets her nieces, Melissa and Imogen. Imogen, like Elise, has psychic abilities, which proves crucial later in the story.

Into the Further

When Melissa is attacked by Keyface and falls into a coma, Elise realizes she must confront the demon within The Further—the dark realm between life and death. She ventures inside, guided by her childhood memories and guilt.

Inside The Further, Elise encounters spirits from her past, including her father. In a surprising twist, her father expresses remorse, allowing her to find some closure. However, Keyface ambushes her, dragging her deeper into the abyss. The demon begins to steal her life force, symbolized by inserting one of its key-fingers into her chest.

At the last moment, Imogen astral projects into The Further to rescue Elise. Together, they overpower Keyface with the help of their mother’s spirit, who intervenes to save them. The family’s emotional reconciliation becomes the heart of the film’s climax.

Movie Ending

Elise successfully destroys Keyface, freeing the trapped souls that had suffered under its power—including her mother. Back in the physical world, Elise and her family share a moment of peace. Elise then dreams of her childhood once more, where her mother’s ghost lovingly hands her a whistle that her brother Christian had lost years earlier—a symbol of their reconnected bond.

However, the ending quickly transitions into familiar territory for Insidious fans. Elise receives a vision of a young boy crying in his room—the boy from the original Insidious film, Dalton Lambert (played by Ty Simpkins). She then hears a familiar demonic growl and sees the red-faced demon from the first movie. This chilling callback seamlessly bridges The Last Key with the events of Insidious (2010), completing the prequel’s timeline and leading directly into the first film.

Final Scene

Elise wakes up from her nightmare, visibly shaken but also content that she has helped others find peace. The movie fades out on her calm face—just before the iconic Insidious sting cuts to black.

Are There Post-Credits Scenes?

No, Insidious: The Last Key does not have a post-credits scene. However, it ends with enough of a connection to the first Insidious that it feels like a natural lead-in rather than needing one. The ending essentially functions as a bridge to the 2010 film.

Type of Movie

Supernatural horror with strong psychological and emotional undertones. It blends ghost story, family drama, and prequel mystery elements to deepen the Insidious mythology.

Cast

Lin Shaye as Elise Rainier
Leigh Whannell as Specs
Angus Sampson as Tucker
Caitlin Gerard as Imogen Rainier
Spencer Locke as Melissa Rainier
Bruce Davison as Christian Rainier
Josh Stewart as Gerald Rainier
Tessa Ferrer as Audrey Rainier

Film Music and Composer

The haunting score was composed by Joseph Bishara, who also appears in the franchise as the demonic entity. His music continues to use dissonant strings, sudden volume shifts, and minimalist motifs to create that signature Insidious sense of dread.

Filming Locations

The film was primarily shot in Los Angeles, California, and Santa Clarita, where the production team recreated Elise’s childhood home. The setting—a decaying desert house near a prison—was chosen to symbolize Elise’s mental and emotional imprisonment within her traumatic past.

Awards and Nominations

While The Last Key didn’t receive major awards, it performed strongly at the box office, earning over $167 million worldwide against a $10 million budget. It’s regarded as one of the more profitable entries in the Insidious franchise.

Behind the Scenes Insights

Lin Shaye called this film “the most personal story” in the series, as it focuses on Elise’s life and trauma.
The demon Keyface was created using both prosthetics and motion capture, performed by Javier Botet—famous for playing horror monsters in Mama and The Conjuring 2.
Director Adam Robitel (also known for Escape Room) said he wanted to give Elise a “hero’s journey,” showing that horror can be empowering rather than just terrifying.
The childhood scenes were filmed first to help the cast emotionally connect to Elise’s backstory.

Inspirations and References

The story draws inspiration from classic haunted-house tales but also explores real psychological themes—childhood abuse, guilt, and repressed trauma. The setting in Five Keys mirrors Elise’s life: five “keys” representing fear, guilt, forgiveness, love, and acceptance.

Alternate Endings and Deleted Scenes

Several deleted scenes expanded on Elise’s relationship with her brother and nieces. One extended sequence reportedly featured more of Keyface’s backstory, hinting that it fed specifically on guilt and female victims, but it was cut for pacing. There are no known alternate endings.

Book Adaptations and Differences

There’s no official book adaptation, but the film’s events align with the Insidious expanded lore novels and comics, which explore Elise’s past and the nature of The Further in greater depth.

Memorable Scenes and Quotes

Key Scenes

Young Elise opening the red door for the first time.
Elise discovering her father’s secret imprisonment chamber.
The first reveal of Keyface’s horrifying key-shaped hands.
Imogen entering The Further to rescue Elise.
The final vision connecting to Dalton Lambert.

Iconic Quotes

Elise: “There’s nothing stronger than a mother’s love… not even death.”
Tucker: “If it screams, don’t follow it.”
Specs: “We’re like the Ghostbusters, but cheaper.”

Easter Eggs and Hidden Details

The number “5” (Five Keys) appears repeatedly—on doors, prison cells, and clocks—symbolizing both the location and the five emotional keys of Elise’s story.
The red door, a franchise icon, represents the entrance to The Further and appears subtly in background shots before its full reveal.
The Lambert family portrait from Insidious can be seen briefly in Elise’s vision at the end.
Keyface’s breathing sound design mirrors the sound used for the red-faced demon in the original film.

Trivia

Lin Shaye was 74 years old during filming, making her one of the oldest actresses to headline a major horror franchise.
The film’s original working title was Insidious: Chapter Four – The Key.
Joseph Bishara composed parts of the score using household objects to create unsettling metallic noises.
The prison seen near Elise’s house was based on a real decommissioned correctional facility in California.

Why Watch?

If you’re invested in the Insidious universe, this film provides the emotional backbone of the series—showing Elise’s origins, her family trauma, and her ultimate courage. It’s less about jump scares and more about closure, identity, and how confronting your past can set you free.

Director’s Other Movies

Escape Room (2019)
The Taking of Deborah Logan (2014)
Escape Room: Tournament of Champions (2021)

Insidious: The Last Key (2018)