At the beginning of the chilling music video, Ziegler is the first to appear, rocking a black wig, rainbow face paint and a dark gray leotard.
The camera then pans to 48 other kids, all dressed in neutral attire with gray-painted faces, lying on a floor. Eventually, they get up to dance with the 13-year-old former Dance Moms star, who leads them out of their caged room.
Ziegler sashays her way through the hallways of the building, at one point walking into a room and making her way to the center of a dance circle. She energetically spins around and around as Sia sings, "I'm free to be the greatest, I'm alive. I'm free to be the greatest here tonight, the greatest."
Towards the end of the video, the ambience changes, as the room turns even darker and white lights and disco balls appear, giving off a dance club vibe. The kids gather together in a tight formation, bopping up and down with their tongues out, before simultaneously falling to the ground.
The video ends with an up-close shot of tears streaming down Ziegler's rainbow-painted cheeks.
While Sia has yet to reveal the true meaning behind the video in her own words, it seemingly pays tribute to the 49 victims who were killed at Pulse nightclub in Orlando in June.
"Humbled to be a part of this video," recording artist Matt Moseley shared via Instagram, accompanied with a screenshot. "Thank you @siathisisacting. 49 beautiful lives lost. This is for you. #WeAreYourChildren."
Ziegler's mother, Melissa Gisoni, echoed Moseley's thoughts, writing, "So excited for this one!! #thegreatest choreography by @siriheffington directed by @danielaskill 49 kids and @maddieziegler #weareyourchildren #sia."
Ziegler has appeared in a number of Sia's music videos -- including "Chandelier," "Elastic Heart," "Big Girls Cry" and "Cheap Thrills" -- and has joined the 40-year-old singer on her Nostalgic for the Present world tour, which kicked off Aug. 4 in Moscow, Russia. The talented duo are gearing up for the North American leg of the tour, with their first show scheduled for Sept. 23 in Las Vegas, Nevada.