[1][2] The movie tells the story of a castaway who washes up on an island and must survive there while being stalked by a humanoid sea monster.

[3] After their boat sinks during a storm, Jennifer "Jenn" Remming washes ashore on a small, tropical island and then finds her friend Brad who dies from his wounds shortly after.

She later buries Brad's corpse in the sand, but she discovers the grave uncovered and a trail of blood leading to the ocean the following morning.

The next day while retrieving her newly surfaced luggage while swimming, Jenn finds an ominous hole in the ocean's floor.

That night, Jenn fails to flag down an airplane using a flare gun and encounters a giant humanoid sea monster.

As Jenn prepares for the fourth night, the corpse of another mutual friend, Zack, washes ashore mutilated and bisected.

When the monster notices the hammock, he starts to touch it and it slowly drops, Jenn stabs the creature with a sharpened stick and narrowly escapes.

The next day, Jenn is reunited with her boyfriend, Lucas Griffin, and friend, Mia Reed, after the two wash ashore in a life raft.

Before setting up a trap for the creature she chronicles her experiences with it in her journal in hopes of aiding any castaways who might wash up on the island after her if she fails.

On February 2, 2017, Blumhouse Productions announced that Kiersey Clemons would star in the film, and J. D. Dillard would co-write, produce and direct.

'"[7] Clemons said the story was a political allegory with a racial empowerment theme: "At the time, we were really reacting to the [2016] election, and the fear of this monster [Donald Trump] being in office.

"[6] The creature, whom the crew nicknamed Charlie, was played by Andrew Crawford, an Australian ballet dancer who had previously been the Xenomorph in Alien: Covenant.

The site's critic's consensus reads: "Carried by Kiersey Clemons' performance, Sweetheart balances smart subtext and social commentary against effective genre thrills.

"[11] Metacritic assigned the film a weighted average score of 71 out of 100, based on 7 critics, indicating "generally favourable reviews".

Dillard delivers a smart, streamlined thriller that skillfully integrates a careful whisper of social commentary into a story that also unfolds masterfully as a straightforward genre workout.

"[13] David Ehrlich of IndieWire gave it a B− and wrote: "What this potent micro-dose of a movie lacks in showmanship, it makes up for in purity and resourcefulness and a rugged performance from Kiersey Clemons".

[14] John DeFore of The Hollywood Reporter wrote of the film: "A cracking little one-hander (mostly) that rations glimpses of its well-designed beastie expertly, the picture will please genre fans who don't mind long stretches with no dialogue.

Jenn has very little backstory, but we get a real sense of her personality just from watching her walk around this idyllic setting or run from the nightmare it turns into.