Set in and around a nameless European city — the film was shot mostly in Germany, but there’s something purposely anonymous about the world Sam (Gillan) and her compatriots and antagonizers alike occupy — “Gunpowder Milkshake” opens with the minimum of information we might need to get invested. Sam is a contract killer, she’s very good at her job, and she loves nothing more than a giant, slurpy glass of ice cream and milk after a job well done. Sam was born into this world, care of her fellow assassin mom Scarlet (Lena Headey), who somewhat unwillingly brought her cute kid (played in flashbacks by Freya Allan) under the sway of “The Firm,” a group of men who are in charge of everything (especially the killer ladies like Scarlet and Sam they employ for their dirty work).

Fifteen years before the film opened, Scarlet went missing after running afoul of some Russian baddies, leaving young Sam to her handler Nathan (Paul Giamatti) and away from the fellow lady assassins of “The Library,” who had previously helped raise her. In the years since, Sam has mostly kept to herself, taking her orders from Nathan and doing her best not to think too hard about her mom or the other wild women who were once such a major part of her life. In the course of her recent duties, Sam kills the wrong guy — the son of a dude The Firm does not want to cross — and is sent on another mission that involves some major unforeseen complications. Suddenly cut off from Nathan and The Firm, Sam (plus one very cute kiddo she picks up along the way, played by the charming Chloe Coleman) must kick a ton of ass in the (perhaps short-sighted) hope of living another day. Reiner Bajo/NETFLIX

Her new self-appointed quest brings her into the orbit of a metric ton of wacky characters, from the “Bonehead” assassins dispatched to off her by Nathan to her mourning, very mad dad Jim McAlester (Ralph Ineson), and even her own mother and the rest of the ladies of The Library (Angela Bassett, Carla Gugino, and Yeoh, a murderer’s row in every sense of the term). Ehud Lavski and Papushado’s script excels at world-building — The Library is a fully formed entity unto itself, but even the secret doctor’s office Sam hits up seems wholly realized as part of this strange universe. But it’s not as adept at navigating the finer points of the story it’s meant to serve. The cutesy, colorful, kitschy details that kickstart the film and keep on pumping through its every high-energy moment help matters, though. There’s the seemingly safe diner that Sam and her fellow assassins frequent for both fun and meetings, set in a puffy, pink space that seems to not totally exist within the neat city which holds the rest of the film’s action. Plus there’s the liberal use of neon signs, split diopter shots, and winking humor. A winking, whimsical mix of “Bad Times at the El Royale,” “Dick Tracy,” every Tarantino film ever made, the “John Wick” universe, and uncloying feminist theory, the whole thing is just fun, sugary as a milkshake, with no brain freeze to worry about. REINER BAJO/© 2021 STUDIOCANAL While the plot leaves plenty to be desired — wait, who did Sam piss off? and why didn’t she visit The Library and the “aunts” who live and work there before this? and what is going on with Nathan? — the relentless zip of the film, plus the pure joy of seeing Gillan and company absolutely wreck their opponents, can’t be denied. Papushado, best known for his more horror-centric outings like “Rabies” and “Big Bad Wolves,” seamlessly transfers his more lethal inclinations to pure action. “Gunpowder Milkshake” is rife with bone-crunching, rib-tickling action sequences, including an early bit that sees Sam going up against baddies without the use of her arms (though aided immeasurably by Coleman’s plucky young Emily), and a last act bloodbath that involves each “aunt” using their best abilities to beat back evil dudes. Yeoh has her chain, yes, but Bassett has a pair of hammers and Gugino a tomahawk. That’s the kind of film this is. Where it all ends won’t surprise anyone. “Gunpowder Milkshake” all but begs for an entire prequel series, even as its final moments quite clearly set things up for a sequel (or more). But the possibilities of a wider universe are tasty enough to support such obvious franchise-baiting. This first entry could stand to be a bit more satisfying on its own, but the sugar rush that accompanies “Gunpowder Milkshake” is more than sweet enough to prove its place in a fast-growing sub-genre, with a cherry on top.

Grade: B-

“Gunpowder Milkshake” starts streaming on Netflix on Wednesday, July 14. Sign Up: Stay on top of the latest breaking film and TV news! Sign up for our Email Newsletters here.