Hollywood always allows itself a little pat on the back when an A-list celebrity turns in a performance as a victim of mental disability.

We had Sean Penn as a retarded father in I Am Sam, Dustin Hoffman portraying an autistic in Rain Man and Nicole Kidman suffering manic depression in The Hours.

So it comes as a welcome relief that a small Scottish film has the courage to actually cast an actress with a real disability in a lead role.

Down's Syndrome sufferer Paula Sage plays Roberta, a bright, sassy youngster who can be as sly as she is affectionate.

Living with her mother May (Duncan) in remote Ayrshire, she seldom sees her elder brother Kenny (McKidd), an ambitious journalist on the make.

His chance at a big time job in the States lies in getting a scoop on a doctor accused of practising euthanasia on the mentally ill.

So it looks like Kenny and Roberta's paths are unlikely to cross...until May discovers she has ovarian cancer.

OK, so it does sound a bit of a mis-fest - Down's, the big C, mental illness and Scottish weather. Oh, and Kenny's got ginger hair.

However, so light and playful is the performance coaxed out of Sage that there's no need to linger overmuch on the less than cheery sub-plots.

In fact, it's just a shame that the story doesn't focus entirely on the struggles of the artistically gifted teenager in a small community.

The euthanasia strand - rather than raise questions over the ethics of assisted suicide - seems superfluous with so much potential drama elsewhere.

In the same way, May's battle with cancer is ladling misfortune on a bit thick while trying the audience's credulity.

It's always laudable to deal with difficult themes...but three at once could be pushing viewer misery thresholds a bit.

The performances throughout are first rate with McKidd's star firmly in the ascendant although Shirley Henderson as his girlfriend is sadly underused.

A gentle, affectionate movie and who can fail to warm to a script that isn't scared to quote The Krankies.

Tim Evans