Having just left prison for setting her ex-boyfriend, serial killer James (Cole Vigue), on fire Mary (Vanessa Grasse) gets a job in an all night gas station. Still haunted by hallucinations, on her first night she begins seeing James around many corners, but there are more dangers in Mary’s first shift than her imagination.

The concept of Padraig Reynolds’ screenplay suggests something more morally complex than your standard issue slasher. He sets up a final girl who isn’t as easy to root for as the genre’s usual heroine, not only did she set someone on fire, but we discover that she has been shunned by the community for simply standing by and watching while her ex murdered several women. This could throw open a lot of ideas; allowing the film to engage with coercive and abusive relationships and the trauma that results from them, the immense pressure building that ended in Mary’s desperate action of trying to burn James to death. Unfortunately, this is almost entirely left as implication, which makes Mary a much less interesting character than she might have been, largely reducing her hallucinations to fodder for scares and setting aside the most interesting aspects of the moral ambiguities the film sets up.

What Reynolds does opt to do, he does efficiently. To call Open 24 Hours a slasher is generically accurate, but strictly speaking it’s more of a basher, as the weapon of choice is generally some sort of hammer. An early claw hammer blow to the face of a supporting character shows that Reynolds and a talented makeup effects team led by Josh and Sierra Russell won’t be skimping on the gore, and so it proves throughout, especially in a sledgehammer death that rivals a similar moment in Pascal Laugier’s Martyrs for grossness, if not for emotional impact.

Vannessa Grasse is effective in showing Mary’s trauma and the visceral effects of her memories of seeing what James did, as well as her day to day difficulties with re-entering the world. This is another reason that it’s frustrating that she doesn’t get much of a chance to deepen that storyline. By the time the climax comes around, Mary is just another final girl and while Grasse pulls that off well enough, it’s still a disappointment. The other performances are mixed, Brendan Fletcher is good as Mary’s co-worker, thrown into a nightmarish situation, but Daniel O’Meara is a little broad as Mary’s parole officer. The raincoat wearing killer isn’t a particularly original image, but Reynolds exploits the menacing silhouette quite well at times, and he does have an effective bit of misdirection earlier in the second act which, again, hints at something tied more effectively to the narrative about the trauma of James’ crimes.

On the whole, Open 24 Hours is like a decent takeaway meal: you can eat it up on a Friday night and feel like you’ve enjoyed it, but a few minutes or hours later you might be thinking that you could have had something more nutritious with the same ingredients.