In THE APP, Niccolo lives in Los Angeles with his beautiful grad school girlfriend Eva. He's an heir to a large fortune and an actor trying to make it on his own who has just landed his "big break," playing Jesus Christ in a movie to be filmed in his home country of Italy. As he makes the preparations to leave for Italy, Eva asks Niccolo to help him with her PhD thesis by downloading a popular dating app called "Us." He reluctantly agrees, and joins the app under the alias "Lorenzo." As he arrives in Italy, checks into his hotel suite, and makes preparations for filming, Niccolo gradually gets sucked in more and more into "Us." He tries to delete the app, but is talked out of it by a mystery woman who stands out from the other sex-centered women he had met up to that point, seeming to know Niccolo a little too well. Niccolo becomes obsessed with meeting the woman, constantly distracted by her texts even when trying to prepare for the movie, and even when Eva arrives in Italy to tell him that she's two months pregnant. He tries to meet with the mystery woman, but they can't seem to connect in person, and she seems to be avoiding him. As Niccolo's life and career begins to unravel around him, the mystery woman finally agrees to reveal her real identity.