There's no question now that Chandelier was the most iconic music video of 2014, and now Sia has put the Chandelier gang back together – with one important addition. Shia LaBeouf becomes the on-screen foil for the precocious Maddie Ziegler in the video for Elastic Heart, with their emotionally turbulent interaction played out within a giant birdcage.

LaBeouf is, of course, a big draw - if any were needed for the sequel to Chandelier. But ultimately this is all about the Art. Like Chandelier it is a strikingly pure exercise in the power of modern dance to express emotion, with great choreography by Ryan Heffington, directed by Daniel Askill with Sia herself. It is a rollercoaster, a tough watch at times as a complex relationship is played out, ultimately over complete silence.

And within hours of it appearing on YouTube, Sia was been moved to defend the video, in response to the public and media reaction to the physical interplay between LaBeouf and the 12 year old Ziegler.

"All I can say is Maddie and Shia are two of the only actors I felt could play these two warring ‘Sia’ states. I apologise to those who feel triggered by Elastic Heart, my intention was to create some emotional content, not to upset anybody,” she wrote on Twitter.

LaBeouf has previous experience in soul-bearing dance-oriented music videos, with his turn in the Alma Har'el-directed promo for Sigur Ros's Fjogur Piano a couple of years ago. And he also appears to share Sia's disenchantment with fame - the kind that tends to attract even more attention (the paper-bag-on head school of anonymity, if you like). But even if Shia was the logical choice for this challenging sequel to Chandelier, no one can accuse Sia of playing safe.