The film - based on Twilight author Stephenie Meyer's novel of the same name - centres on humans fighting against aliens called 'Souls' who invade bodies and wipe their victims' consciousness.
The Host's movie adaptation will see Atonement actress Ronan play the lead character Melanie Stryder, as well as the alien called Wanderer, who takes over her body.
William Hurt, Diane Kruger and Max Irons are also among the cast of the sci-fi/romance project from director Andrew Niccol.
> Chandler Canterbury, Boyd Holbrook join Saoirse Ronan in The Host
Watch Saoirse Ronan discuss The Host with Digital Spy below: