‘ANYTHING that makes people happy can’t be bad. Can it?”

It's the sort of line you'd expect to hear emerging from the mouth of a child in Mary Poppins. The words are, in fact, spoken, by a naive young woman at a Nazi parade, and they characterise a film that is as gauche as it is well-meaning. Indeed, Good may be the queasiest attempt to address the Holocaust on film since Roberto Benigni's disgusting Life Is Beautiful.

Adapted from a play by CP Taylor, Good addresses the perilous question of what turns a decent German into a Nazi. Hiding behind a strange English accent, Viggo Mortensen plays John Halder, a university lecturer who attracts Hitler’s attention when he writes a novel that touches on the subject of assisted suicide.

As the film begins, Halder is living a hectic but largely happy life with his bohemian wife, clever children and increasingly senile mother. His best pal (Jason Isaacs), a Jewish psychiatrist, warns him against having too much to do with the new administration, but, eager not to lose his job, Halder agrees to write a paper for the ministry.

An hour into the film, he is wearing an SS uniform, living with a younger woman and advising his friend to leave the country. “You have no ties here,” Halder says to the pal, who was born in Germany and fought in the previous war.

Far from changing gradually from acquiescent naif to guilty collaborator, Halder makes random quantum leaps from idiot to genius and, when the creaky plot demands, back from boffin to dunce in equally rapid measure.

Indeed, Mortensen, though reliably charismatic, seems to have decided to play at least seven distinct characters – cynic, Pollyanna, fascist, humanitarian, etc – without allowing any one of them an ounce of nuance. He is not helped by the clichéd dialogue and a barmy theatrical device that has passers-by warble bits of Mahler at moments of high drama.

However, none of this prepares the viewer for the jaw-dropping finale. Finally confronted with a concentration camp, Halder widens his eyes, grasps his head and begins to reel with shock and disbelief.

I know how he feels. Who knew that such places looked like Butlin’s and that their rosy- cheeked inmates were quite so well fed? Not good. Not good at all.

GOOD Directed by Vicente Amorim. Starring Viggo Mortensen, Jason Isaacs, Jodie Whittaker 15A cert, Kino, Cork; Screen, Dublin, 96 min*