In terms of casting, directorIra Sachsadopts a daring strategy in “Passages.”

The film tells the story of an amazing creep, a married gay man who cheats on his husband with a woman, and then lies to and manipulates both of them. To have someone like that in your life is a form of pestilence. The only thing you can do is get away.

So who does Sachs cast in this role? You’d think he’d cast someone superficially appealing, someone handsome or magnetic or lovably idiosyncratic. You would think he’d do that to make sure that we understand, and to some degree even feel, the hold that this man has on his two partners.

But no. Instead, Sachs casts Franz Rugowski, who does his best here to look and act like the world’s creepiest creep — and he succeeds.

As Tomas, Rugowski isn’t allowed to have a single moment of charm, not a glimmer of light. Even before we know that Tomas is a bad person, Sachs shows us that Tomas is bad at his job. In the first scene, Tomas is directing a movie, and we see him abusing his actors and insisting that they imitatehiminstead of finding their performances within. Tomas is a rare portrait of a man without a redeeming feature; just standing there, he’s mildly repellent.

Yet there’s genius in this choice. After all, haven’t we all had this experience: Your friend tells you how they’re in the thrall of some horrible boyfriend, and then you meet the guy. Does he ever look like Brad Pitt? Is he ever as charming as Cary Grant? Never. Instead, almost invariably, it’s someone who makes you wonder how this sad situation is even possible. What is the power that this creep holds over your otherwise sane friend?

(goldman Sachs)提出了一个答案:或许som的力量eone like Tomas derives from the thoroughness of his awfulness. If he were any less terrible, he’d question his own behavior, and radiate doubt. But because he’s a complete narcissist, he has the gift of absolute confidence. He can brazen his way into a career in the arts and into a series of relationships because his unworthiness never occurs to him.

In an early scene, Tomas is having a cast party in a Paris nightclub, and he’s annoyed that his husband, the long-suffering Martin (a downcast Ben Whishaw) wants to leave. So Tomas starts dancing with a young woman, Agathe (Adéle Exarchopoulos), and the two end up in bed.

To give you an idea of the kind of personality Sachs is presenting, when Tomas returns to Martin the next morning, he doesn’t apologize. Instead, he wants to tell Martin about how the sex with Agathe opened a different side of himself, and how wonderful it was. He is such an egomaniac that he really believes Martin should be interested.

This is hilarious, but not in the way that provokes laughter. The experience is more one of jaw-dropped bemusement. Exarchopoulos and Whishaw play people who are entirely sympathetic, as we see them being out-maneuvered by a guy that has no business being in either of their lives. That Tomas is entirely unworthy is emphasized over and over throughout the movie, but always in painfully interesting ways.

Young people should see “Passages” for warning and instruction. They need to recognize the Tomases when they turn up, because people like Tomas can use up years of a person’s life.

Reach Mick LaSalle: mlasalle@sfchronicle.com