Let’s get the business of the title out of the way. It’s an acronym for “retired, extremely dangerous.” It’s a catchphrase label put on Frank Moses (Bruce Willis).

Frank is leading a life of retirement in Cleveland: up every morning at 6 o’clock and keeping a spare, neat home. But he’s lonely. He tears up the pension check he gets each week in the mail, then calls and complains to Sarah (Mary-Louise Parker), the office drone in Kansas City who promises to figure out what happened to the check.

That R.E.D. stuff comes in when a murderous masked guy with big guns pays a visit to Frank who, without breaking a sweat, takes the guy out, then heads to K.C. with hopes of meeting Sarah.

But what do you get when a dangerous former black-ops CIA agent gets together with a wide-eyed innocent gal? You get a rocky start to a relationship, played out by both actors with amusing finesse, making good use of physical comedy and fast, snappy dialogue.

Frank, forcibly retired because of his age, soon finds a hit list with names of other R.E.D.s, many of them friends of his. So we’ve got a road-trip movie, made up of visits to warn some old working pals including Joe (Morgan Freeman), Marvin (John Malkovich) and Victoria (Helen Mirren).

This is a sly, funny, elegant action film for adults, with surprises around every corner — and lots of corners. Disguised as a thriller about “old folks” who are just itching to get back into the game, the script ventures into political intrigue and the idea that being bad can be quite intoxicating. Sweet little Sarah soon becomes an accomplice in this affair, regularly shouting out “Cool!” and “Awesome!” in response to the mayhem around her.

It’s too bad there isn’t more of Ernest Borgnine as a crusty CIA records keeper, but that’s almost made up for with a great performance by Brian Cox as Ivan, a former Russian agent who was once on the other side of Frank’s espionage.

The best part of it all? Some will say the inclusion of a little romance, while others will choose the clever throwaway comic lines from most of the cast, or those big guns and bigger explosions, or the fact the movie doesn’t keep you guessing — it keeps you off-guard. I liked the giddiness among these characters, because they realize that they’re actually out there doing it all again. And Helen Mirren looks really hot behind a high-powered rifle.