One of the most underrated films of the past decade has got to be “Adventureland,” the 2009 coming-of-age comedy by Greg Mottola (“Superbad”). It mined its setting — a rundown 1980s amusement park — for plenty of jokes, but it had a fantastic bittersweet feel to it as well, capturing that moment of drifting aimlessly between college and “real life” well.

Best of all was the chemistry between its two leads, Jesse Eisenberg and Kristen Stewart, who were both still young at the time, but confidently mixed goofy humor with something more poignant. Unlike so many teen comedy actors, they managed to capture an affection that seemed real.

Thus, I was looking forward to “American Ultra,” a new comedy that reunites the pair. Having now seen it, I’d like to take director Nima Nourizadeh and dangle him off a tall building until he squeals for mercy like a stuck pig. How on Earth could you sign these two actors but create a piece of crap as pointless as this? Nourizadeh takes the “my boyfriend/girlfriend is a spy/assassin” action genre and mixes it with a half-baked attempt at stoner comedy. He succeeds at neither. “American Ultra” plays like an episode of “Homeland” for people too stoned to process the plot of a “SpongeBob SquarePants” episode.

Eisenberg plays Mike, a long-haired nerd who works at a convenience store, smokes a lot of skunk weed and suffers from crippling panic attacks. Kristen Stewart plays Phoebe, his perfect-looking, totally supportive dream girlfriend. Mike just wants to figure out a way to propose to her that won’t involve another panic fit, while Phoebe is, like, just, really there for him.

It takes about 10 minutes for us to find out that Mike is actually some kind of brainwashed government-secret-super-soldier, who can take out armed thugs with nothing more than a spoon. The bad guys at the CIA want him dead, except for the other good guys at the CIA who are trying to help him, and yadda yadda yadda. There are vague references to Project MKUltra — the CIA’s real-life LSD-tainted mind-control program — but they’re barely developed, and besides, “The Men Who Stare at Goats” got there first.

Eisenberg and Stewart aren’t bad, but they fail to leave an impression. You can watch him doing neurotic and needy or her doing tough-yet-vulnerable in a dozen better films. John Leguizamo turns up doing a decent impersonation of James Franco from “Spring Breakers” but, beyond that, you’re scraping the bottom for anything resembling entertainment. Connie Britton and Topher Grace play CIA higher-ups who spend the entire movie bickering like 12-year-olds who just learned their first cuss words.

“American Ultra” features some jokes that aren’t all that funny, some action that’s not all that exciting and some plot twists that aren’t in the least surprising. Like another recent film, “Moonwalkers,” it features a pretty high level of gore and violence for a comedy. More thought seems to go into one headshot squib than the entire script. Anyone in the mood for a teenage super-assassin flick should rent “Hanna” (2011), which is basically the same premise but done with flair and guaranteed to deliver an adrenaline charge.

Truth be told, the real blame here should lie with screenwriter Max Landis, who is living proof that nepotism is alive and well in Hollywood. There is no way this poor excuse for a screenplay could get you through the door unless your father is director John Landis (“Animal House,” “The Blues Brothers,” etc.).

Then again, “American Ultra” is so wildly unoriginal and formulaic that I wonder if “Max Landis” is an actual person, or the prototype of a screenwriting algorithm. Hell, Eisenberg even looks furtively at the camera at one point and mutters, “What if I’m, like, a robot?” Indeed.