Emily Blunt has a new movie. You may have heard of it. It's called The Girl on the Train, and it's an adaptation of the book you've definitely seen everyone around you reading during your commute to work. It premiered in London Tuesday evening, and in lieu of a red carpet, Blunt and her co-star Haley Bennett walked a faux-railway complete with a faux-train platform. Their elaborate premiere looks were anything but commuter wear, though — for Bennett, a Valentino couture creation that oozed Renaissance glamour with its gold sparkles and off-the-shoulder silhouette, and for Blunt, a bright, every-color-of-the-rainbow Alexander McQueen embroidered gown. Just a few days earlier, Blunt sat front-row at Michael Kors in a cute polka-dotted ensemble by the American designer — perched next to fellow Brit It girls Sienna Miller and Cynthia Erivo, also in Kors — but now, she's traded in her American digs for England's finest.

Emily Blunt in Alexander McQueen at the premiere of The Girl on the Train in London, England, September 2016.

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Who: Emily Blunt.

When: Tuesday, September 20.

Where: The world premiere of The Girl on the Train in London, England.

What: A rainbow, floral-embroidered sheer Alexander McQueen Resort 2017 column gown with a pearl and gold flower crown woven into her updo.

Why: In The Girl on the Train, Blunt plays an alcoholic woman who becomes obsessed by a couple she sees on her daily commute — and even more so when the woman, played by Bennett, goes missing. It's a dark role, and one sharply at odds with Blunt's choice of red carpet look — a bright, cheerful McQueen ensemble with boho undertones, especially when it comes to the crown woven into her slightly messy updo. McQueen's Sarah Burton also designed a nearly identical gown in slightly darker tones for the Resort collection. Yet for the premiere of one of her darkest films yet, Blunt keeps it cheerful, like a little woodland nymph in high fashion.

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