Safety Not Guaranteed pulls off an extremely hard hat trick: It’s a smart movie about time travel that delivers comedy as well as heart and soul.

It’s like a unicorn, but better. (And with Aubrey Plaza.)

Science fiction isn’t known for sweet, romantic comedy tinges. While sci-fi movies can occasionally be funny (like Paul) and every now and then one contains a romantic subplot (usually not too believable or even very clear (::cough:: Prometheus ::cough::), such films rarely, if ever, do both well.

That makes Safety Not Guaranteed, which opened in a few theaters last week and is expanding into more cities this weekend, a rare find.

(Spoiler alert: Minor plot points follow.)

The premise of Safety Not Guaranteed, directed by Colin Trevorrow, comes from an internet meme: a wanted ad seeking a partner for time travel that found its way onto You’re the Man Now Dog. In the film, a group of magazine staffers try to track down the author of the classified ad, Kenneth (played by Mark Duplass). To get to him, they send their female colleague Darius (Plaza), who ends up being charmed by Kenneth’s oddball ways.

“It is a sensitive, relationship-oriented, time-travel movie. I hadn’t seen that before and I love that that was a challenge to try to pull off.”

“It is a sensitive, relationship-oriented, time-travel movie,” Duplass told Wired back in January, when the film screened at the Sundance Film Festival. “I hadn’t seen that before and I love that that was a challenge to try to pull off.”

Exactly how they pull it off we’ll leave for your theater-going experience, but suffice to say that Duplass and Plaza do an incredible job of making one of the more off-the-wall geek love stories in recent memory totally believable. Add to that the fact that Parks and Recreation‘s Plaza is on top of her comedy game throughout the film, and you’ve got the best actually romantic funny date movie for nerds to see this summer.

Yes, there have been funny sci-fi films before, even ones that had to do with time travel (like Back to the Future), but the romance in such flicks often feels forced and/or just a little off. (Remember when Marty McFly’s mom fell for him? Yeah, that was weird.)

Likewise, some great romantic comedies have incorporated sci-fi elements, but they’re not always that great with the, you know, science. (That crap that went down in What Women Want where Mel Gibson can hear women’s thoughts was just, like, whatever.)

It’s obviously hard to get everything to gel when you’re trying to make a sci-fi film that’s funny as well as reliably romantic.

This isn’t to say that there was never a good sci-fi-tinged rom-com — Groundhog Day was pretty good — but it’s hard to find a good example. (iO9 tried a while back and also came up pretty blank.) But the makers of Safety Not Guaranteed have managed to add one flick to the incredibly small pile.

In a blockbuster summer full of alien and superhero movies that are definitely bringing the action, but maybe not a lot of heart or laughs, Safety Not Guaranteed offers a welcome respite.

Blowback: What’s Your Favorite Sci-Fi Rom-Com?

Think we’re wrong about the small number of good sci-fi romantic comedies? Share your favorites in the comments below.