An aimless stoner given to unexplained panic attacks kills a pair of seasoned assassins in a convenience store parking lot using only a dull ramen spoon, and starts to display other wild self-defense skills he couldn’t possibly have. It transpires that he’s a newly activated, very lethal sleeper agent for the CIA.

What a great premise! Borne meets the bong! Someday someone will make a hilarious, exciting movie out of such a twist. This isn’t it.

A clever conceit alone is not enough, and this uneven, one-joke genre mishmash never decides what it wants to be. Whether you like Tarantino or not, few have been able to match his ability to combine violence with humor. This is too light for an action movie and too serious for a stoner comedy, so it seems to have settled for being a relentlessly bloody, gore-over-wit B-movie with unrelenting ultraviolence.

There’s also a sweet slacker romance in the mix, but it often seems to be peeking in from a different movie.

It is in spots undeniably inventive. Like a MacGyver-inspired battle in a big box store, using anything at hand as weapons. And the interaction between stars Jesse Eisenberg and Kristin Stewart is almost worth sitting through all the gratuitous bloodletting. But the film offers little new or interesting to the old activated-sleeper-agent trope.

A low-grade, ultra-forgettable buzz that’s sporadically entertaining with a few awkward laughs. Take some munchies. Stay for the closing credits.

Japanese title: Agent Ultra. (96 min)