Roger Ebert, though best known for raising or lowering a pudgy digit, is also one of our wisest philosophers about the movies. And with the taut suspense thriller Red Eye, we see proof of one of his most insightful maxims: “A good movie is never too long, and a bad movie is never too short.”

That little koan has often been interpreted as a defense of epic running times against those whose ass alarms go off at the two-hour mark. But it also works the other way--smart filmmakers make movies that are exactly as long as they need to be functionally. Good movies, no matter their length, are lean and efficient; bad movies, no matter their length, feel bloated and unfocused. This is why Ebert was also flirting with a proof of Einsteinian physics principles about the relativity of time: 82 minutes of Deuce Bigalow: European Gigolo could not possibly have felt more like it sucked away precious years of my life, while the 85 minutes of Wes Craven’s Red Eye snapped along with an almost perfect sense for making its story work.

That story--in the tradition of some of the best in its genre--isn’t terribly complicated. Lisa Reisert (Rachel McAdams), a Miami hotel manager, is returning home after a family funeral; Jackson (Cillian Murphy) is a charming-seeming fellow who chats her up while they’re waiting for their delayed late-night flight from Dallas back to Florida. But Jackson has an ulterior motive: He’s part of a plot to assassinate a Homeland Security official who’s staying in Lisa’s hotel, and he needs her to make a call moving the target to a specific room. If she doesn’t, someone is waiting outside the home of Lisa’s father (Brian Cox) to kill him.

It’s the time-tested cat-and-mouse game, only with the cat and mouse trapped together in a shoebox. Craven may be a director best known for horror fare like A Nightmare on Elm St. and Scream, but the guy knows how to work a sequence in a claustrophobic space; anyone who recalls the nerve-jangling police car escape from Scream 2 will get the picture. While the stuck-on-a-plane situation would seem to be the kind of thing that might run out of gas fast, screenwriter Carl Ellsworth--a TV veteran doing his first produced movie work--keeps finding new ways to twist the scenario.

It gets even better once the plane lands (and don’t even step to me, spoiler police). Through a sharply-crafted chase through the airport and a whole lot of home-invasion creeping about, Craven ratchets up the tension as the clock ticks down on the plot’s twin perils: Can Lisa prevent the planned assassination, and can she save her father.

Hollywood throws genre fare like this at us on a near-monthly basis, but it’s really only when you see a cleanly constructed example like Red Eye that you realize how badly most of them botch it. This one starts with an easily embraceable protagonist--McAdams (Wedding Crashers) has the kind of charm and charisma of which real movie stars are made--and a great, challenging villain. Both characters are written smart and resourceful, which makes it so much more enjoyable when they do the little things that movie characters so rarely do--like checking behind the shower curtain--thus making them seem like morons. Lisa’s wounded backstory might feel trite, but here it works at upping the ante and making her emotional struggles feel more potent.

Another whole column could be devoted to the tiny bits and pieces that add spice--a flight attendant with a garbage bag judgmentally delivering the line, “Trash?” after Lisa and Jackson have emerged from the airplane’s restroom; Jayma Mays as Lisa’s harried underling at the hotel--and just generally allow you to leave the theater feeling that you’ve been well and truly entertained. But the simpler truth is that Red Eye works mostly because it’s simple: primal conflict with all the fat stripped away, delivered with energy and style. Like Die Hard or Speed, Red Eye grasps the fundamentals of tight editing, strong character and apparently hopeless situations. When its 85 minutes have run their course, you may grasp that this movie works because you’d be hard pressed to think of a reason it should have been a minute longer, or a minute shorter.

RED EYE

***1/2 (three and a half stars

Rachel McAdams, Cillian Murphy, Brian Cox.

Directed by Wes Craven

Rated PG-13.