Who knows, in a few years time Fun Size may prove memorable for having kick-started the big screen careers of its stars Victoria Justice and Jane Levy, but there’s certainly nothing memorable about the film in its own right. Justice (star of TV’s Victorious) plays Wren, a nerdy but beautiful teen who is saddled with looking after her mischievous 8-year-old brother Albert on Halloween, meaning that she and her best friend April (Levy – star of Suburgatory and the forthcoming Evil Dead remake) can’t attend Aaron Riley’s Halloween party. Who’s he you ask? “Aaron Riley – God. Stud. Legend,” we’re reliably informed (without a hint of irony) as Aaron drives his convertible sports car in windswept slow motion. Things go from bad to worse for Wren (and the audience) when Albert goes missing, prompting a frantic search for him that inevitably only causes more trouble.

The set-up is reminiscent of a whole host of better movies. Wren’s frustration with her brother but desperation to find him again recalls Labyrinth. The night of mayhem that will end at a cool house party is lifted straight from Superbad – a tamer version of which Fun Size desperately wants to be. The lost child behaving badly storyline brings to mind Home Alone, Dennis and Baby’s Day Out. Yes, even Baby’s Day Out is better than this movie, and that really shouldn’t be the case. Justice and Levy both do their jobs capably and are effortlessly likable, but that’s about it when it comes to what there is to like.

Despite a couple of early witty lines, the dialogue in Josh Schwartz’s debut directorial feature lacks any kind of rhythm – and that’s bizarre when you consider that Schwartz was the man responsible for the early, well-paced and unexpectedly entertaining episodes of The OC. But that was Josh Schwartz the writer, and with writing duties going to another feature debutant Max Werner, Schwartz fluffs his lines with shoddy direction that saps the scenes of any of the zip they should have. And when the witty lines dry up, Schwartz is left with a structurally inept script that constantly throws its under-developed characters into madcap situations without any logic or reason.

Levy and Justice don’t even get the screen time that they not only deserve, but that their stories should demand. We spend an inordinate amount of time with Albert, there’s a subplot involving Wren’s mother (Chelsea Handler) that never justifies its existence, and Wren’s nerdy friend and admirer Roosevelt worms his way into proceedings enough that it’s he who we’re ultimately asked to root for come the final act. It doesn’t help either that Roosevelt is played by one of Project X’s three almighty douches, Thomas Mann, who proves just as irksome when he’s supposed to be the adorably geeky guy.

Fun Size’s failures are made all the more frustrating because there’s obviously enough talent involved and the nugget of a good idea hiding in there somewhere that could have made for a Halloween treat. But instead the result is rather more trick than treat – which means it’s about as fun as having eggs thrown at your front door.