The film begins in a mysterious underwater setting, where the voice of Giles (Richard Jenkins) narrates a poignant tale about a princess, her beloved, and the monster that seeks to keep them apart. Set in Baltimore during 1962, we meet Elisa Esposito (Sally Hawkins), a mute woman living in solitude, yet often sharing moments with her neighbor, Giles, a bachelor who spends his days dreaming and creating ads for jello.
Elisa works the night shift at the Occam Aerospace Research Center alongside her friend Zelda Fuller (Octavia Spencer). During one such shift, they come across a mysterious vessel containing an extraordinary creature, known as the Asset (Doug Jones). Curiosity sparks within Elisa when she witnesses something move inside the vessel, setting in motion a journey that will change her life forever.
In a light-hearted moment after work, Giles treats Elisa to his favorite key lime pie at a local shop, where the Pie Guy (Morgan Kelly) serves them. However, their camaraderie is soon tested when Colonel Richard Strickland (Michael Shannon), an abrasive figure at the research center, suffers a grotesque accident that leaves him maimed, amplifying the sense of danger surrounding them.
Elisa's fascination with the Asset grows as she sneaks into its enclosure, feeding it hard-boiled eggs, teaching it sign language, and sharing music, forging an unlikely bond. This sanctuary is shattered when Strickland tortures the creature, showcasing his cruelty drawn from personal frustrations in his family life. Meanwhile, a new character, Dr. Robert Hoffstetler (Michael Stuhlbarg), is revealed to be a spy navigating complex loyalties, where he contemplates the potential intelligence of the Asset.
Feeling a kinship with the creature, Elisa decides to risk everything to save it from Strickland's impending plan to destroy it. Giles reluctantly agrees to assist, and together they devise a plan to rescue the Asset. This onslaught of personal courage culminates in a tense escape sequence aided by Zelda and Hoffstetler, leading them to Elisa's apartment, where a secret world unfolds—the Asset is more alive than anyone could have imagined.
As their connection deepens, Elisa and the Asset engage in a shared intimacy that transcends societal norms. Their passionate bond unfolds in a bathing ritual filled with dreamlike sequences and potential freedom. A menacing situation escalates as Strickland, desperate and deranged, discovers Elisa’s plan to release the creature into a canal.
In the film's climax, Strickland confronts them at the canal, where the tension explodes into violence. Just when it seems Elisa's fate is sealed, the Asset displays newfound powers that turn the tide of destiny. In a dramatic twist, it heals Elisa, allowing them to finally embrace their love beneath the water’s surface.
As Giles narrates the closing moments, their connection blooms, signaling a transcendent union that defies the confines of their world. This poignant tale drives home the message of understanding and love without barriers, making it a masterpiece of romance and fantasy that lingers in the heart.
