I don’t quite know how to feel about Say When. With the tagline: “a comedy about acting your age and other adult decisions”, I was not feeling particularly enthused on the way to Cineworld. But I have to say, I did enjoy it – it’s an easy watch, but not one that I would watch again.

Titled ‘Laggies’ in America, meaning “those who lag behind”, the premise of the film is that Megan (Kiera Knightley) is suffering from a ‘quarter-life crisis’. She is stuck in a rut: dating the same guy since high school, working for her dad’s sign company and having very few plans for the future. She finds solace in Annika Hunter (Chloë Grace Moretz), a 16-year-old who Megan sees as a kindred spirit. They become friends and, in search of escape from her life of adult decisions, Megan ends up having a weeklong sleepover with Annika and, in doing so, almost reverts to adolescence. But wait – there’s more, and that’s where the ‘rom’ in ‘rom-com’ comes in. Annika happens to have a very handsome father, Craig Hunter (Sam Rockwell), who, by chance, is single. He and Megan certainly have chemistry. Will she? Won’t she? These questions must be asked. However, despite the definite focus on romance, the film is much more about self-discovery and acceptance.

The plot itself is ridiculous: what 16 year old girl would allow a 28-year-old woman, even if it is Kiera Knightley, to stay for a week long sleepover? But this improbable storyline is delivered in a charming way and the relationship between Megan and Annika is convincing and endearing. Highlights include an absolutely stellar wedding dance to Daniel Bedingfield’s ‘I Don’t Want to Run Away’ by Allison, Megan’s best friend from high school played by Ellie Kemper, and the improvised scenes showing the madness of teenage girl existence, between Annika and Misty (Kaitlyn Dever), her school friend. Plus the scenes in which we see the Hunters’ tortoise, which is frankly a great addition to the film.

It’s not the most original or inventive movie – there are quite a few clichés – but hey! In choosing to go to a rom-com, you are choosing to be smacked in the face with cliché after cliché, and the director, Lynn Shelton, does it well. It’s an admirable performance by Knightley, Rockwell and Moretz. I definitely never imagined Keira Knightley, arguably the nation’s sweetheart, with a convincing American accent while skateboarding, but in Say When she delivers both.

It’s a far cry from Lizzie Bennet and Anna Karenina, but not an unwelcome shift. Rockwell is also good, performing the charming male lead commendably. As for Moretz, in a film about acting your age and achievment, there is no one more depressing to see – 17 years old and already doing ridiculously well, you can understand why Megan wants to spend a week basking in her adolescent glory. Moretz has mastered the art of playing the slightly sullen but endearing teenage girl – definitely a tricky balance. The cast carries the film and I imagine that Knightley’s foray into American rom-coms will be successful, although probably not a box office smash.

I don’t know whether watching a film about being unemployed, overqualified and hiding just to escape it all is a good idea half way through term, but Say When is engaging enough to make it worth it. Light and amusing, it’s easy to enjoy. However, if you are looking for something illuminating or revelationary, I would argue that it probably won’t fulfil your expectations.