WELCOME TO PARADISE: Caleb (Domnhall Gleeson, left) is greeted by the CEO and owner of his employer Nathan (Oscar Isaac). After winning a company wide lottery, Caleb was rewarded with a visit to Nathan’s mountain retreat. As it turns out, Nathan had an ulterior motive. He wants Caleb to evaluate his latest fembot to see if she can pass the Turing test, which means that she can pass as being a human instead of a cyborg. (Photo © 2015 — Universal Pictures International)

Caleb Smith (Domnhall Gleeson) is a computer programmer for Blue Book, the most popular internet search engine in the world. When he wins a staff lottery, he is summoned to the hilltop retreat of the company’s reclusive CEO, Nathan Bateman (Oscar Isaac).

After being brought there by corporate helicopter, he discovers that his billionaire boss has a hidden agenda. As it turns out, the place is really a high-tech facility that is conducting research in artificial intelligence.

In order to stay, Caleb is required to sign a non-disclosure agreement in which he promises to keep secret what he’s about to witness. Nathan next explains that an android has been invented, and he wants to see if it will pass the Turing test — which means that the software will be examined for signs that reveal the android is not human.

He then introduces Caleb to Ava (Alicia Vikander), a beautiful fembot that he wants Caleb to study for a week. Caleb is surprised by her level of sophistication, since her brain is complex enough to discern the meaning of idioms like “breaking the ice.” He’s even more impressed by her non-deterministic nature, as she appears to have been successfully programmed to have free will.

The plot thickens several days into the project when Ava senses Caleb has developed feelings for her. At that point, the attractive automaton quietly confides her fears about being expendable. She claims that Nathan wouldn’t have a second thought about wiping her memory banks clean once she’s no longer considered to be state-of-the-art. She points out that that’s what he’s done to each of her predecessors in his quest to build a better cyborg.

Where does Caleb’s loyalty lie? With the callous employer whom he suddenly sees as a heartless tinkerer? Or with the flesh-covered machine that exhibits a full range of emotions, including a seductive vulnerability? That is the dilemma confronting the anguished protagonist in Ex Machina, an intriguing science fiction adventure that is the directorial debut of Alex Garland. Best known as the scriptwriter of 28 Days Later, Garland proves he is a capable filmmaker here, with a thought provoking thriller that is guaranteed to keep you enthralled.

Excellent (****). Rated R for profanity, violence, sexual references, and graphic nudity. Running time: 108 minutes. Distributor: A24.