Conan O’Brien, A$AP Rocky, and Danielle Macdonald co-star in Mary Bronstein’s audacious anxiety nightmare.

What will surely go down as one the most stressful movies of the year is “If I Had Legs I’d Kick You,” which premiered Friday at the Sundance Film Festival.

Mary Bronstein's 'If I Had Legs I'd Kick You' wowed the Sundance Film Festival with an all-time Rose Byrne performance.

Contrary to its title, everyone in If I Had Legs I’d Kick You has their appendages. Rose Byrne’s protagonist, however, does have a wealth of problems and neuroses, and writer/director Mary Bronstein dives into her headspace with a full-bore intensity and immediacy that’s bracing at first,

Creator Mary Bronstein and star Rose Byrne stop by THR's studio in Park City to dish all about their film If 'I Had Legs I'd Kick You.' They break down the meaning behind the movie, the difficulties of motherhood and more.