Phoebe Waller-Bridge has hauled herself out of the bath she sat in for Jack Thorne's Mydidae at the Trafalgar Studios earlier this year and plonked herself on a bar stool in the middle of an Underbelly brick cavern in Cowgate.

She's fully clothed, but laying herself emotionally bare in a grown-up girl's cautionary tale of sex in the city, public porn and private parts, what not to say to your own father and how best to deal with a sister whose stepson has the hots for her, like Hippolytus for Phaedra. Waller-Bridge doesn't labour any such allusions, nor harbour any more illusions, but she does come across as an angry, vengeful commentator on her own background and experience, and this gives the hour-long tirade its energy and its tremendous bite.

If anyone can declaim lasciviously from a great height while crouched on a stool, Waller-Bridge can, her limbs flailing quietly but exasperatedly by her side, dark hair piled in a coiled bunch, eyes flashing round the room as she spares us none of the gruesome detail in her professional humiliations (in a café with guinea pigs) or sexual encounters (not with guinea pigs).

There's something raw and different about this upper middle-class femme fatale, a smart and haughty madam brought low by her own wide-ranging experience and limitless aptitude for critical disappointment. A sharp-edged gem of a solo show.

Fleabag continues at Underbelly, Cowgate until 25 August (not 13)''