The Downton Abbey star opted for a Lanvin dress with a cinched-in waist and halter-style top. She paired it with Rupert Sanderson shoes and an elegant chignon and was, quite frankly, the epitome of demure.
Julianne was equally beguiling wearing a floor-sweeping Balenciaga dress and clutch, Christian Louboutin shoes, and Boucheron jewellery.
The film sees Liam Neeson play an air marshal who springs into action during a transatlantic flight after receiving a series of text messages that put his fellow passengers at risk unless the airline transfers $150 million into an off-shore account.
It also stars 12 Years A Slave hit Lupita Nyong'o and Hell On Wheels hunk Anson Mount.
Love Julianne? Flick through her style file below: