Director Tim Fywell makes the leap from small to big screen with "I Capture the Castle", an enjoyable if sudsy growing pains yarn adapted from the popular novel by Dodie Smith.

It stars Romola Garai as teenager Cassandra Mortmain, an aspiring writer who documents the lives of her oddball family, resident in a dilapidated castle in 30s Suffolk.

Cassandra has a thorny relationship with her father (Bill Nighy), a self-indulgent novelist suffering from creative block, and is resigned to living in the shadow of her beautiful sister Rose - played archetypically wild and wicked by Rose Byrne.

When their estate is inherited by Simon, a well-heeled American socialite (Henry Thomas), Rose wastes no time sinking her claws into him. It's a source of consternation for his younger brother (Marc Blucas) who secretly covets Rose, and for Cassandra, who rather inconveniently falls in love with Simon.

You get the picture. It's "Pretty in Pink" in period costume.

Historical setting (and use of the word 'covet') aside, the telling of Cassandra's passage into maturity has all the wit and worldly savvy of a John Hughes classic.

Newcomer Romola Garai is suitably reminiscent of teen angst queen Claire Danes. As well as the physical resemblance, she also possesses that familiar combination of soulful and sanguine.

Although her performance does sustain interest, the plot falters in the last stages when Cassandra is forced to reconcile conflicting desires.

It's where Fywell betrays his television roots; by allowing Cassandra's indecision to send the narrative back-and-forth he almost stalls it completely. Ultimately this makes the story feel rather protracted, like a two-part miniseries tacked together.

Even so, "I Capture the Castle" combines enough subtle humour and honest insights to offer a welcome antidote to the recent slew of gross-out teen flicks more concerned with baring ass than baring soul.