Mackenzie Davis in Talks to Join Kristen Stewart in Same-Sex Rom-Com 'Happiest Season' (Exclusive)

The holiday-set feature centers on a young woman whose plan to propose to her girlfriend while at her family’s annual party is upended.

Mackenzie Davis is in talks to join Kristen Stewart in TriStar's lesbian romantic comedy Happiest Season.

The movie centers on a young woman whose plan to propose to her girlfriend while at her family’s annual holiday party is upended when she discovers her partner hasn’t yet come out to her conservative parents.

The studio had no comment on Mackenzie's casting, but The Hollywood Reporter has learned that Davis and Stewart will be playing the film's romantic leads.

Actress-turned-director Clea Duvall will be making her studio directing debut on the feature, which she co-wrote with Mary Holland. The project will be produced by Temple Hill's Marty Bowen, Isaac Klausner and Jaclyn Huntling. Hannah Minghella and Shary Shirazi will oversee the project for TriStar.

Davis broke out on the AMC series Halt and Catch Fire, going on to book roles in such big-budget studio films as The Martian and Blade Runner 2049. She also has been tapped to star in Tim Miller's upcoming Terminator reboot, joining franchise stars Linda Hamilton and Arnold Schwarzenegger.

Davis is repped by UTA and Sloane Offer.