High schoolers Julie (Kathryn Newton), Kayla (Geraldine Viswanathan) and Sam (Gideon Adlon) make a pact to each lose their virginity on prom night. When their parents (Leslie Mann, John Cena, and Ike Barinholtz) inadvertently find out, they hastily rush out to spoil their daughters’ plans.

Blockers, helmed by first-time director Kay Cannon, is a new movie comedy. To cut to the chase: it is not entirely great. It has plenty of great performances, and is well directed, but its screenplay regularly stumbles and its basic premise instinctively feels odious and wrong. The film struggles to be two comedies at once, and while one feels like an enjoyable variation on the Superbad teen comedy the other is a weak and regularly ugly story of three grown adults going out of their way to ruin their children’s lives. It is quite east to engage with the former, but rather difficult to root for the latter. By the time the two plot threads awkwardly collide at the climax, the damage is pretty much done. It is difficult to imagine this particular prom night comedy being remembered that fondly in years to come – that is assuming it is remembered at all.

That’s a real shame, because the rest of the film does its damnedest to overcome the premise and deliver some genuinely amiable laughs. The three teenage protagonists are very appealing and believable. They are also neatly varied: Julie is the love-struck and gushing romantic, Kayla the agreeable stoner, and Sam the closeted gay geek who spends time in her room photoshopping her head into photographs from Xena: Warrior Princess. All three work together well, and generate a huge amount of audience goodwill. Their own personal journeys – and their decisions on whether or not to go through with having sex on the night – feel empowered and comparatively sensible for this kind of a film. Like several other recent movie comedies, Blockers also gets a lot of mileage out of using women to challenge the male-centric stereotype of these kinds of movies. All three actresses are excellent, but it is Geraldine Viswanathan who jumps off the screen in comedic terms. I can see her having a long and successful career in comedy if she wants to.

Sadly the adult half of the film does not work half as well. This is despite good comedic performances by Cena, Mann, and Barinholtz. Suspension of disbelief simply stretches way too far in a gross-out, raunchy odyssey of anally consumed beer, unwanted sexual activity and exploding cars. Of the three Leslie Mann has it worst: having to play out both unattractive decisions and awkward-as-hell comedic bits that do not do her character any favours at all. John Cena can play a funny caricature, but the thinness of his character contrasts poorly with the more well-rounded teenage leads. Of the three it is surprising Barinholtz that is gifted with an honest-to-god character with a proper narrative arc and more than one dimension. He begins the film threatening to be its most egregious character and winds up the most believable and resonant of the three adults.

There are plenty of funny moments, but it never feels like there are quite enough to paper over the film’s critical flaws. It leaves one fairly unsatisfied: the film definitely rises above its premise, but the bottom line is that it simply does not rise enough. It would be good to see Cannon working with a stronger screenplay – ideally one she has written herself next time – and actually provides the number of laughs required to really make a film enjoyable.