“The Earth is at peace. Our world has never been more perfect.” The opening lines to director Andrew Niccol’s newest sci-fi film ring throughout the movie theater as the camera zooms in on what appears to be Earth. Only it is not “our” world anymore.

“The Host” takes place in the future after the Souls, a group of aliens who invade human bodies, have taken over the planet. After years of running, Melanie Stryder (Saoirse Ronan) is captured, and the alien Wanderer is inserted into her body to recover her memories and find the last human resistance. But Melanie’s conscious doesn’t fade away as the other humans did, and she is able to communicate with Wanderer, or Wanda, by speaking in her mind. She convinces Wanda to run from the Souls and find Melanie’s brother Jamie (Chandler Canterbury) and Jared Howe (Max Irons), her lover. When the two girls find the human resistance, a complicated attraction forms between Wanda and Ian (Jake Abel), another human.

Ronan’s performance was second to none. She didn’t struggle in the slightest with the challenge of playing two very different characters at once. She expertly displayed the calm serenity of a Soul and the aggression of a human fighting for her body. One of the film’s finest moments is an extended close-up scene on Ronan as she switches between playing Melanie and Wanda with such emotion that the scene is bound to affect even the most stoic of viewers.

Throughout the movie, there is an interior dialogue between Melanie and Wanda, which can be a bit difficult to understand, but it adds a much-needed sense of humor to what could have been an otherwise dull plot. Niccol throws in goofy digressions, temper tantrums and snarky comments that keep the audience laughing. During a romantic moment, Ian asks Wanda, “Is there any way Melanie can give us some privacy?” to which Melanie snorts, “You wish!” offscreen.

Despite the silly inner commentary, there are many serious moments that are escalated by a lovely and heart-wrenching score by Antonio Pinto. The guitar solos and gentle strings fiddling in the background of the quiet moments between Wanda and Ian or Melanie and Jared escalate the romance of the scenes. The dry and spare landscape also adds a strange sense of beauty, giving the film a more haunted guise.

Fans of Meyer’s novel may be disappointed to know that a few key aspects of the plot were changed. Melanie, who is supposed to be trapped and immobile inside her own head, has control of her body in the film. She practically forces Wanda to leave civilization to go in search of Jamie and Jared, which, in the novel, was a distinct choice of Wanda’s. It symbolized the alien’s selflessness and her growing love for Jared and Jamie.

“The Host” may be a bit confusing to viewers who have not previously read the novel, but the humorous moments from a cast of talented actors and beautiful score combine to create an entertaining sci-fi film.

Three stars.

Strong acting compensates for confusing plot in sci-fi film “The Host.”