Irish teen actress Saoirse Ronan, already an Oscar nominee at 12 years of age for her role in Atonement in 2007, kicks butt, literally, in her upcoming film The Host, based on a novel by Twilight author Stephenie Meyer.

Given Meyer’s huge popularity The Host has hit written all over it, so Ronan’s star is set to soar even higher given that she’s got the lead part as Melanie, the heroine of Meyer’s sci-fi/romance novel.

“A body-snatching alien takes possession of a girl who refuses to surrender her mind, and together they seek out the man they both love” – that’s the synopsis of the novel as provided by Moviefone, which also interviewed Ronan about not using a stunt double for some of the film’s trickier scenes.

Ronan, 18, proves she can get crazy on screen just like an old pro. “I like doing my own stunts because it’s always going to look more realistic,” she says.

One scene had her character jumping off a balcony, and Ronan was more than game to strap a harness on and do it herself.

“[The crew] asked me if I wanted to – apparently they were having bets that I wouldn’t do it,” Ronan said.  “I proved them all wrong.”

The film opens on March 29, and also stars Diane Kruger, William Hurt and Jake Abel.  You can Google Saoirse to see her on Moviefone – no doubt we’ll be hearing a lot more from her as the opening date approaches.