Following in the footsteps of his big brother James, Dave Franco makes his directing debut with The Rental, an insipid and immature horror-thriller that never finds a sense of place or purpose. Franco tries to shake up the well-worn slasher genre by throwing in the romantic hang-ups of the mumblecore genre, but he doesn’t seem to have the mechanics of either genre down. Existing at the intersection of Drinking Buddies and I Know What You Did Last Summer, it lacks both the amiable character chemistry of the former and the over-the-top gory kills of the latter.We’re introduced to co-workers Charlie (Dan Stevens) and Mina (Sheila Vand) as they drool over a oceanview AirBnb. Since they just finished a big project, they reward themselves by booking it for a weekend away. Along with Charlie’s wife Michelle (Alison Brie) and Mina’s boyfriend/Charlie’s brother Josh (Jeremy Allen White), the group makes their way to the picturesque rental property. The sweet deal starts to sour when property manager Taylor (Toby Huss) gives them creepy vibes right from the get-go and it doesn’t take long for unresolved sexual tension to rear its ugly head. After making other unsettling discoveries about the house, the four vacationers become the target of a series of violent confrontations from an unseen force.The setup for The Rental — four friends going away for the weekend — is about as old as the slasher genre itself, so the devil, as they say, is in the details. The biggest issue with the film is that the screenplay, co-written by Franco and Joe Swanberg, doesn’t adequately capitalize on this hackneyed jumping-off point. Although Mina is certainly the most likable of the four friends, all of the characters are generally repugnant in their behavior and are increasingly difficult to empathize with. It certainly doesn’t help that Franco indulges some improvisational banter from the quartet, particularly a banal set of exchanges interpolating the word “bro.”Franco also carries forth another proud tradition of bad slasher movies: dumb people making dumb decisions just so the plot can move forward. These four seem to be in their mid-30s, yet they have the decision-making abilities and childish senses of humor that would seem more in-line with a misfit group of teenagers. As the circumstances behind the characters’ stay become deadly, several obvious solutions emerge only to be brushed aside in favor of other hair-brained schemes. It all leads to a head-scratching anticlimax topped off with some overbearing social commentary about The Way We Live Today. That the most chilling portion of the movie plays out over the end credits tells you everything you need to know about the previous 88 minutes.Perhaps fitting for the on-screen buffoons, there are amateur mistakes made off-screen as well. While some of the cinematography by Christian Sprenger takes advantage of the idyllic locale, several key shots are sloppily rendered and unnecessarily murky. The editing by Kyle Reiter cuts away from or omits so many shots of potential violence that it almost seems like they were shooting for a PG-13 rating. Normally I wouldn’t dock a film for holding back on violent images, but when we’re talking about a slasher movie, modesty is often not a virtue. If the ScareBnb horror subgenre is to continue, it needs better torch-bearers than The Rental.