So when the Sundance Film Festival books a film whose plotline is described as, “This gripping tale of love, lust, and the power of friendship charts the unconventional and passionate affairs of two lifelong friends who fall in love with each other’s sons,” you figure that the results would have to be smarter and more complicated than the porn-y premise on the surface, right?

Wrong! “Two Mothers” may be based on a novel by Doris Lessing and adapted to the screen by director Anne Fontaine (“Coco Before Chanel”) and prestige hack Christopher Hampton, with Naomi Watts and Robin Wright in the lead roles, but it’s an exceedingly silly, sun-baked sex movie, the kind of import that adds just enough brains to its genitals to get into U.S. arthouses. (In the ’70s, the mothers would have been played by Laura Antonelli and Sylvia Kristel.)

What you think happens, happens: Lil (Watts) and Roz (Wright) grow up on the Australian coast as best pals, and eventually give birth to hunky surfers who could pass as Abercrombie models. Lil’s 20-ish son Ian (Xavier Samuels) initiates an affair with Roz, and Roz’s son (James Frecheville) does likewise to Lil, and we’re off to the races. We’re not, however, going to get a single adult conversation about the implications or morality or even logic of this set-up.

Instead, Fontaine gives us scene after scene of swimming and surfing and sun-bathing. At first, it’s an interesting motif, to make these characters seem more bonded with nature than with the human world. (None of them seem to have any friends outside of the two families.) But after spending an hour in the ocean, the movie gets as swollen and wrinkly as the characters’ fingers.

Watts and Wright, naturally, act the hell out of this piffle, and at the Sundance premiere, Fontaine seemed genuinely taken aback that the audience laughed at it throughout, so clearly the intention was to make a serious drama and not just a beautifully-shot (by Christophe Beaucarne) mix of the worst of Lifetime and Cinemax.

Nonetheless, the resulting movie is basically Buff Teens and the Cougar MILFs Who Love Them.

Elsewhere at Sundance, the documentary “God Loves Uganda” inspired the kind of audience outrage the director actually intended.

Remember when tobacco companies started stepping up their marketing in the third world because their former customer base became much less interested in their toxic product? The same thing is happening with U.S. evangelical churches and their rabid strain of aggressive homophobia.

Now that their message is finding less and less of a foothold at home, these churches are off to spread their hate in Africa, where denounced preachers and “doctors” can be taken seriously and even influence government policy.

That’s what’s happening in Uganda, where the parliament has been considering a “kill the gays” bill for several years. Director Roger Ross Williams (director of the Oscar-winning short “Music by Prudence”) connects the dots between the virulent anti-gay politics in contemporary Uganda and the U.S. churches that are exporting their fringe views to the country in the guise of charity and mission work. (The Ugandan pastor of one of the affiliated churches is now, not coincidentally, one of the nation’s richest men.)

The bill before Parliament would imprison gays and even execute “repeat offenders,” and while it has not yet been passed, its mere existence as a bill — coupled with the Ugandan media’s collusion with the evangelicals — has led to violence against the nation’s gays, including the murder of prominent activist David Kato. And lest the movie be accused of religion-bashing, we hear from several pro-gay Ugandan clergy who have faced excommunication and exile because of their liberal views.

Williams noted in the Q&A that the American evangelicals (mostly from an organization called IHOP, or International House of Prayer) happily participated in the film -- knowing that he didn’t share their views -- because they wanted the world to behold their work. Those less inclined to swallow what IHOP is serving up will find “God Loves Uganda” chilling and disturbing, but they’ll also be inspired to find out what they can do to curb that country’s human rights violations.