A few decades in the future the Earth is suffering serious environmental problems and an associated economic depression. Diseases wipe out entire food crops while dust storms sweep across the landscape.
Matthew McConaughey is a former astronaut now trying to do his part as a farmer. He's also raising a teenage son and a 10-year-old daughter with the help of his late wife’s father (John Lithgow). The public has turned against such frivolous luxuries as space exploration, and the daughter gets in trouble at school for disputing the new textbooks that claim the Moon landings were Cold War propaganda and never really happened.
But it turns out NASA is secretly still a going concern where a team of scientist headed by one of McConaughey’s college professors (Michael Caine) is trying to come up with a way to save humanity, or at least as many people as possible, and to that end they want McConaughey and a small team of colleagues, including Caine’s daughter (Anne Hathaway) to take a spacecraft into a wormhole that’s been discovered in orbit around Saturn. The other end opens into a distant galaxy near some promising planets for colonization. But the cold equations of relativity may leave an uncrossable gulf between the astronauts and the people back home.
I don’t recall any other movie that so successfully combines high emotion with hard sf. One of the film’s executive producers is CalTech theoretical physicist Kip Thorne, famous among other things for a series of bets with Stephen Hawking about future discoveries in general relativity. The visuals for a scene set near a black holes event horizon were computer generated based on serious numerical analysis of some heavy-duty gravitational physics and the results turned out to give some new physical insights that led to at least one published scientific paper on black holes as well as another on computer graphics.
There are some implausibilities in the plot and some might find it over-dramatic, but on the whole this is one of the better examples of honest-to-goodness science fiction on film I’ve ever seen, and I recommend it.
As a bonus, here's Neil deGrasse Tyson on the science of Interstellar. Be aware that there is one mild but non-trivial spoiler in the latter half. (For what it's worth, had I seen this before viewing the film I don't think that would have made a significant dent in my enjoyment.) At several points Tyson makes a some interesting general remarks about artistic license versus strict scientific accuracy and about science fiction as social commentary.