After she manically orders a huge amount of furniture, telling neighbours her husband won it on a TV game show, she's sent to a mental institution.

Shaz terrifies the girls into obedience with her ocker accent, her dog Ripper and the knife she keeps in her cowboy boot, but she also encourages them to stand up to local bullies including their smarmy Aunt Doris, their snobbish, house-proud neighbour Nancy and the two mean girls who run the local coffee shop, who always forced Shirley to eat unwanted donuts.

He tells Coral that Shaz is convinced the spirit of their daughter, who died in a boating accident, is trapped inside the giant preserved shark in Trevor's exhibit.

Tortured by the gentle guitar songs of his guard, Trout, Trevor manages to escape just in time to intercept and reason with Shaz as she attempts to free the shark from its tank and 'release' it into the ocean.

Director PJ Hogan based the script on his own mother's mental breakdown when he was 12, and his politician father's refusal to tell anyone about his wife's illness in case it hurt his electoral chances.

"[2] When shooting Muriel's Wedding, Hogan and his producer wife Jocelyn Moorhouse would entertain Toni Collette with stories about the real 'Shaz'.

The site's consensus reads: "Mental is a well-acted black comedy that suffers from jarring tonal shifts and a lack of comic discipline".

Pomeranz gave it four out of five stars, saying director PJ Hogan "walks a fine line between the grotesque and the compassionate and for me, he succeeds, painfully but gracefully."

"[6] In The Age, Craig Mathieson was more cautiously positive, noting the film's "brash, consumptive energy that turns on everything from diagnosing mental illness and race relations to shark imagery and teenage affirmation.

That's partly why Mental is so strongly unique, so difficult to contextualise, so easy to herald as a triumph of ballsy suburban dramedy or an ambitious dud."

But Buckmaster gave it a favourable review: "It is a bare-all everything-in-the-open film, and the way it encourages discussion of important issues without appearing didactic or preachy is admirable.