Review/Drama/SARA (R21)/94 minutes/Opens tomorrow/**1/2

The story: After teenager Sara (Charlene Choi) is sexually abused by her stepfather (Tony Ho), she runs away from home. She meets a senior government official Kam (Simon Yam), who enrols her in a top school and pays for her education after they start an affair. Fast forward to almost a decade later, she is a journalist who travels to Chiang Mai, Thailand, and crosses paths with underage prostitute Dot My (Sunadcha Tadrabiab).

For all the hype over this being girl-next-door star Charlene Choi's first erotic film, the supposedly steamy sex scenes are all rather tame.

Some of the most provocative shots are already featured in the movie trailer, which makes the R21 rating for this film surprising. She is never seen fully naked and some of her bedroom scenes are only implied.

Credit is nonetheless due to Choi for attempting something out of her comfort zone, especially for a star whose popularity has hinged on her sweet, goody-two-shoes image.

The singer-turned-actress, who is one half of Hong Kong pop duo Twins, shows potential here as a serious dramatic actress, although probably not quite as deserving of all the acting awards and nominations heaped on her of late.

She is most convincing when she plays the fiercely independent journalist, a young woman who is indignant for her causes and fights for what she feels is right.

But when it comes to portraying the fragile, more delicate side of the character, she is horribly one-note - think a lot of blank stares.

The bigger culprit than her lack of serious acting experience is an overstuffed script.

Director Herman Yau and screenwriter Elaine Lee - both of whom collaborated on the equally lacklustre Ip Man: The Final Fight (2013) - attempt to do so much at once that everything feels superficial.

The film cries out for more depth to the troubled relationship between Sara and her mother, who did nothing when her stepfather raped her.

And Sara's relationship with Kam is perfunctory at best, told in a series of brief flashbacks that tell nothing of their true feelings for each other.

Does he love her or is it just the sex he loves? It is hard to tell.

Worse is her attempt to rescue Thai prostitute Dot My - there is nothing believable about her motivation. The link is tenuous between her wanting to help someone else as Kam once helped her.

It is a pity that, for the most part, this earnest and well-meaning film feels like a missed opportunity to shed some light on the plight of underage prostitutes in South-east Asia.