StarSolidStarSolidStarSolidStarOutline(3 stars)

Revenge is best served online in director Safy Nebbou’s riveting psychological thriller “Who You Think I Am.” This provocative and sexy tale of Internet identity is thoroughly entertaining. But for the movie’s twists and turns to make sense, you have to buy the idea that young men would reject the affections of a successful, 50-something professional who looks like Juliette Binoche.

The veteran actress stars as Claire, a college professor and single mother who tells her story to a skeptical therapist (Nicole Garcia) throughout the film. You see, it all began when Claire’s husband Gilles (Charles Berling) left her for a much younger woman. Claire then got involved with Ludo (Guillaume Gouix), young enough to be her son.

Ludo abruptly ends their relationship — he won’t even accept Claire’s friend request on Facebook. So she fabricates a profile, calls herself Clara and pretends to be a 24-year-old intern. Before she knows it, Claire — or Clara — is having a steamy, disembodied affair with Ludo’s roommate Alex (François Civil), a 24-year-old photographer desperate to meet this intriguing yet elusive woman.

How romantic! How 21st century! After moving on to more intimate phone calls, Claire is genuinely besotted with Alex, but she’s reluctant to see him in person and thus admit her deceit. As Claire’s mood goes from despondent to reinvigorated, her virtual sex life begins to take precedence over her parental responsibilities. In one scene that plays as both funny and unsettling, Claire drives circles around a school parking lot while her children wait for her to stop and pick them up — all so she can talk to Alex without letting on that she’s a middle-aged mother. But what would be so wrong with revealing that?

To some degree, the central premise of “Who You Think I Am” is old hat. “Catfish,” the controversial documentary whose title became synonymous with online deception, was released in 2010. But the clever script by Nebbou and co-writer Julie Peyr, adapted from Camille Laurens’s 2016 novel, injects new life into familiar Internet dating tropes of caution and reinvention. Claire’s lies are born out of a particular loneliness: that of a great beauty who’s terrified she’s lost her looks.

Even if you don’t believe a 50-something professional wouldn’t know what Instagram is, Binoche is as magnetic as ever, whether she’s being naive or conniving. As the melodrama swells into surprising (and at times hilarious) detours, she rises to the occasion, drawing powerful emotions out of a plot that revolves around Facebook. And although he’s little more than a pawn for much of the film, Civil eventually brings a vulnerability to his boy-toy role. With a tone that shifts as much as a profile picture, “Who You Think I Am” is a nail-biting ride through social media anxiety.

Unrated. At Landmark’s E Street Cinema. Contains nudity and sexual situations. In French with subtitles. 101 minutes.