Watch: Matthew Williamson Celebrates 15 Years With 'XV' Fashion Film

Thanks to Frankenstorm, we've had more than our fair share of Halloween tricks. Here comes the treat.

To celebrate the 15th anniversary of his eponymous label, Matthew Williamson has rounded up some famous fashionista pals and whipped up an exhilarating assortment of decadent gowns for 'XV,' a fashion film airing on and produced by Swarovski.

The video starts with the designer hearing a woman call his name as he watches dancers from the Royal Ballet and muses like Poppy Delevingne—looking gorgeous in a teal peacock gown—prance about in his candy-colored creations.

Keep your eyes peeled for a unicorn, reams of silk spilling out the windows Rapunzel-style, and Sienna Miller, who rocks a red beaded number with feathered accents as she blows out a birthday cupcake.

The best part? That voice calling Matthew's name is actress Andrea Riseborough, who plays the part of the designer's harried mother in an amusing flashback.

"He thinks he's bleeding Yves Saint Laurent," she huffs as she tries to get the teenage Matthew off to school.

Just wait, Mom.