The Black Swan actress, 30, will take on the role of a free-spirited traveller named Vivian who turns up unexpectedly at Walden’s house.
Walden Schmidt, played by Kutcher, believes Vivian is his soulmate, despite having been on the verge of proposing to another woman.
Kutcher and Kunis, who have been dating since spring 2012, last appeared in a scripted TV programme together on Fox’s That ‘70s Show in 1998. The pair starred as on-off high school lovers Jackie and Kelso for eight seasons of the show.
Speculation over her reported engagement began last week, when Kunis was spotted wearing a sparkling ring while shopping in Los Angeles. Kunis posted a photo on Instagram of the couple kissing, with a caption reading: “Happily ever after”.
The pair have not confirmed or denied the reports, but 36-year-old Kutcher's divorce to actress Demi Moore was finalised in November 2013.Reuse content