It’s a play about sex workers. And Katie Jarvis is hooked.

"I'm not like you."

Not a bit like you, other characters in Band of Gold waste no time in telling the sex workers they meet.

The police officer who sleeps with the sex workers isn't like them.

The councillor who uses their services isn't at all like them.

The audience watching a play about sex workers definitely, definitely isn't like them.

We're not like Anita (wonderful Laurie Brett) with the fabulous voice (belting out Human League songs almost as if she is human), whose married lover, George (Mark Sheals), will leave his rich wife and move in with Anita and her pink sofa… given time. In the meantime, the important thing is that he pays her bills.

We're not like Rose (outstanding Gaynor Faye), who shot up heroin not knowing she was pregnant. When the baby was born - 16 years ago now - it instantly took after its mum: cried and shook as if already a junkie.

We're not like Carol (fab Emma Osman), who takes on any punter who'll pay her but who exercises her disgust by repeatedly scrubbing her toilet with bleach.

And we're definitely, definitely, DEFINITELY not like Gina (I'm running out of superlatives; but, hey, Sacha Parkinson!), who has left her violent husband.

"He does one thing wrong and you kick the poor bugger out," her downtrodden mum, Joyce (Olwen May), berates her.

"It wasn't the first time he hit me, mum!"

"Well, you must have done something wrong… Take him back, love. I bet he's sorry. He won't do it again."

And maybe Joyce is right. Because the alternatives turn out not to be so great after all.

But Sacha has a child to support - husband Steve (Kieron Richardson: the male actors may not be granted the range of the women but all are equally convincing) will only give her money if she lets him move back. (Not that he's got any; not his fault he was laid off.) Anyway, Gina's stint as an Avon rep doesn't work out. So what alternatives has she left?

Writer Kay Mellor - who, of course, first aired Band of Gold on ITV, to mass acclaim - spent 10 months speaking to sex workers in Leeds and Bradford, trying to learn their language; aiming to understand their lives. What she discovered is the obvious: that women with money, support, and happy childhoods don't need to sell their bodies. Those who face poverty, children they can't feed, an addition they have to feed; those are the ones out on the dangerous streets, getting into stranger's cars. Watching out for each other because no one else will. "Back then - in the late 80s/early 90s, a young mother would only have child benefit and income support to live on, which sometimes could be as little as £45 a week. How on earth were they supposed to live on that?"

This isn't Pretty Woman (one of the films I loathe most in the world; how dare they). It doesn't pull its punches. The transfer to stage works brilliantly. This is a detective story (with Shayne Ward as the excellently understated Inspector Newall); it's a drama; it's got music; it's very funny. It's utterly horrifying; it's deeply moving.

The backdrop is depressingly perfect. The pace - particularly in the first half - keeps you hooked.

By the end, we're empathising, understanding, buddying with these women who are not like us.

"What is disturbing," Kay Mellor says, "is that today there are even more women driven to sex work to make ends meet. The introduction of Universal Credit, years of austerity and cuts have sadly hit the most vulnerable people in our society. Nobody is tackling the real root cause of sex work: poverty."

Band of Gold, by Kay Mellor, at Cheltenham Everyman, Monday, March 2 - Saturday, March 7

The Everyman Theatre is at Regent Street, Cheltenham, Gloucestershire GL50 1HQ, box office 01242 572573; www.everymantheatre.org.uk