Most of the remarkable videos Sia has made with dance muse Maddie Ziegler explore the singer's personal struggles. We've seen intimate, heart-rending portraits of Sia's battle with addiction and troubled relationship with her dad. But Sia's latest Maddie collaboration, the video for "The Greatest," transcends the personal: It's a tribute to the victims of the Orlando nightclub shooting. Sia's own anger and sadness about the terrorist attack—which Maddie portrays so eloquently—become a moving expression of a larger community's fury.

"The Greatest" also includes some of Ryan Heffington's most compelling choreography yet. In addition to Maddie, the video features a cast of 49 young dancers—to mirror the 49 victims of the Orlando tragedy—who swarm and writhe and, finally, fall to the floor as if shot. (The group includes a lot of our favorites, by the way: Look for Larsen Thompson, Sean Lew, Kerrynton Jones and Stephanie Mincone in the grey-faced crowd.)

The cast of "The Greatest" (screenshot via YouTube)

Heffington's choreography has always made dancers seem like pots about to boil over, bubbling with barely-contained frustration. Here, that distinctive style feels especially apt. You'll probably recognize a few of the signature steps from his fun-crazy "Cheap Thrills" choreo, but they take on a totally different shading in this context.

TL;DR edit: You need to watch this RIGHT NOW.

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