Let's just get it out of the way here: This is not the trailer for Disney's Little Mermaid remake, with music by Alan Menken and Lin-Manuel Miranda, one of a whole slew of live-action adaptations that the studio has planned.
The girl's older brother Cam (William Moseley) is a reporter, and travels with his sister to a small town in MS to find the maybe-mermaid in question, who is played by Downton Abbey's Poppy Drayton.
Confusingly, it shares a title, "The Little Mermaid", with the animated classic.
This new film is based more on the original Hans Christian Anderson fairy tale rather than Disney's Ariel version which we are more accustomed to. However, in this film, it's her soul instead of her voice that is controlled by that person. But this version offers a twist on both the Disney fairy tale and its Hans Christian Andersen source material: A reporter (Moseley) and his little sister travel to a small MS town to find the real "little mermaid", who seems to have secured a gig in a circus act.
The mermaid told Peralta that there is a legend among the people about a little girl who is blessed with a soul of a mermaid. And look, Shirley MacLaine is there, too, telling stories about mermaids to youngsters, and we are already 99% sure she is actually the little girl from the story when she grows up.
Extra confusingly, it's not the only "The Little Mermaid" film in the works.