Midway through a recent screening of “Vacation,” the lights in the theater unexpectedly came on, leading this viewer to wonder: Can I go now? Alas, darkness descended once again, leaving the audience stuck in the mindless hell that is the Griswold family, bumbling toward Walley World.

Part remake, part sequel, the movie follows Rusty Griswold, the son in the original 1983 “National Lampoon’s Vacation.” There, he was played by Anthony Michael Hall; here, Ed Helms picks up the baton, portraying the now-grown Rusty as a dweeby pilot for a budget airline. Taking a break from puddle-jumping, Rusty has decided to drag his wife, Debbie (Christina Applegate), and their two sons on a road trip from Chicago to Los Angeles — by way of Memphis, for some reason — simply to ride a roller coaster called the Velociraptor.

We already know this story: Misadventure ensues, starting with the family’s car rental, a lunchbox-on-wheels imported from Albania, with a navigation system that speaks only Korean.

Let’s hope Rusty bought the insurance.

Writer-directors John Francis Daley and Jonathan M. Goldstein seem to think that the “angry”-sounding Korean language is inherently funny. It’s not. Neither are the film’s jokes about rape, pedophilia and suicide, nor the cameo by Chevy Chase, who starred in the original film, but who hasn’t been funny in ages. Pushing the envelope is great, but only when some intelligent thought goes into the nudging.

Rusty Griswold (Ed Helms) aims to top his childhood trip to Walley World as he drags his two boys and wife on a cross-country trip to the beloved theme park. (  / Warner Bros. Pictures)

Instead, we get items checked off of a to-do list. Along with the requisite gross-out humor, cleavage shots and hot-pants-clad booty-shaking — courtesy of a detour to a sorority — we also get a half-hearted stab at sweeter sentiments. The trip is supposed to be a way for Rusty to reconnect with Debbie, who has grown bored with their marriage. Rusty also hopes the drive will bring his sons closer. James (Skyler Gisondo) is a sensitive, guitar-playing, journal-loving teen who is perpetually bullied by his little brother, Kevin (Steele Stebbins), a mini-terrorist with a mouth like a sailor. Kevin at one point puts a plastic bag over James’s head in an attempt to suffocate him. Nothing says comedy like fratricide.

And what bonds a family better than mistaking a reservoir of raw sewage for a hot spring? If the movie’s many other unsavory moments don’t turn you off — including pools of vomit, orgies and a head-on collision that kills a woman in a convertible — just wait until you see Rusty spraying a mouthful of sewage into the air while Debbie rubs therapeutic “mud” all over her face.

There are a couple of mildly amusing moments centering on Debbie’s attempt to show up her younger sorority sisters by chugging a pitcher of beer and running an obstacle course. But the cleverest detour involves a quartet of police officers jockeying for jurisdiction at the Four Corners monument, where Colorado, New Mexico, Arizona and Utah meet.

For the most part, “Vacation” is a sad, cynical rip-off of writer John Hughes’s source material. No one expects originality, but the new movie may end up making history: It’s already looking like the worst movie of the year.

R. At area theaters. Contains crude and sexual content, coarse language throughout and brief graphic nudity. 99 minutes.