Dame Elish Angiolini has a great plan for Scotland's only women's prison.

She wants it reduced to rubble. She's right. Nothing quite prepares you for a visit. The sights, sounds and smells of the place resonate in your mind long after you emerge from "The Vale", a low grubby 1970s complex perched awkwardly on the edge of posh Bridge of Allan.

The blonde angelic tiara-wearing tot, clinging to her granny's hand as they await a "supervised play session" with mummy, a mentally scarred drug addict. (What was that figure Kenny MacAskill quoted the other day? Half the children of women jailed in Scotland end up in prison themselves.)

The pleading wail from behind a locked cell door as we pass: "A'm needin' the toilet, a'm needin' the toilet ..." (Didn't Hugh Monro, the prisons chief inspector, complain in his report that at night women sometimes waited an hour to relieve themselves? Dignity? What dignity?)

Then there's that institutional stench of disinfectant and too many women squeezed into too little space. (Even with 100 moved to Edinburgh's Saughton, women sleep three to a cell because the number being sent to prison has almost doubled in a decade, despite falling crime levels. We're told there are instances of "enforced lesbianism". I'd call that rape.)

Bleakest of all are the isolation cells: claustrophobic windowless boxes containing nothing but a steel toilet, a thin mattress and tear-proof bedding. ("So that they can't use it for ligatures," explains governor Teresa Medhurst, who looks tense and tired. She adds that after a rash of suicides in the 1990s, "the absolute priority in this prison is to keep these women alive".)

Yes, that is her proudest boast. She's had women throwing themselves over balconies and swallowing bleach but she hasn't lost anyone. It's a measure both of how desperately ill and sad most of these women are and of how badly broken Scotland's female penal system has become. Even the Victorians entertained notions of rehabilitation. Yet here, with so much overcrowding and so many inmates on remand or serving short sentences, there is little scope for anything beyond feeding and stabilising them. About 80% come back in, so it's also a lousy deterrent.

Left-leaning critiques often involve misogynist sheriffs disproportionately incarcerating women. The truth is more complicated. It's partly to do with society's increasingly zero tolerance attitude towards criminal behaviour, especially among girls and women. It's partly because of the closure of the big mental hospitals. Many of these women would have been incarcerated in them a few decades ago. The biggest factor is the explosive growth in drug and alcohol-related violence among women.

The sum of all this is a hard core of very damaged women with chaotic lives. Many or most have suffered abuse and/or periods in care. They are bad at keeping appointments with courts, doctors and social workers. Faced with serial non-appearances, ultimately a sheriff has little choice but to issue a warrant for arrest.

So they end up in Cornton Vale and their lives fall apart. A woman imprisoned for longer than a month will lose her local authority tenancy. Separated from her children, she loses her reason for living. She'll emerge, having learned to be a better criminal, with a cheque for £65 but can't get benefits for five weeks. What would you do?

Ms Angiolini's Commission on Women Offenders is out next week. It's her parting shot before swapping her life in the Scottish justice system for the green lawns of an Oxford college and she wants to be listened to because, as she says: "There have been 10 previous reports about this and not one has been implemented." She's likely to call for Cornton Vale to be demolished and a much smaller secure unit, built somewhere more accessible for visitors, to house the small minority of serious violent offenders serving long sentences. Minor offenders would be housed in small centres spread around the country and supervised by prison officers, social workers and mental health specialists. Yes, it will cost a lot to mend this broken system but ultimately it'll cost a lot more not to.