DiCaprio is slated to play Rick Dalton, a real-life former western TV star, and Pitt is set to play Cliff Booth, who worked as his stunt double.
With this much star power, it's either going to be the best thing we've ever seen or a total flop — there is no in between.
The film is set in the 60s and Dalton just happened to live next door to Sharon Tate, who was famously murdered by the Manson Family.
Tarantino is playing this whole ordeal very close to the vest but Manson will very likely play a part in the story. We have good intel to back that assertion up too — "Once Upon a Time in Hollywood" is scheduled for release August 9, 2019, and that's (drum roll, please) the 50th anniversary of the LaBianca murders and the day after Sharon Tate's. Both massacres were carried out by the Manson Family.
Margot Robbie is rumored to be taking on the role of Tate.