Canadian company Parry Riposte plumbs the criminal underbelly of interwar London through the story of one of its most fearsome figures in their first visit to the Fringe. A tripartite monologue delving into the bloody history of the city's most notorious all-female gang, The Elephant Girls develops from a shaky start into a shaded, sophisticated exploration of love, violence, and the disastrous consequences of their meeting.

It's an unremarkable opening. As retired criminal Maggie Hale, whose shoplifting, pickpocketing, and honey-trapping exploits the show follows, Margo MacDonald's performance initially feels hammy. She mugs for the audience, contorting her features into a cheap caricature of hard-man masculinity, and Hale's proud brags of the gang's exploits are rendered dull by this contrived delivery.

But as the monologue develops, and Maggie becomes more accustomed to her unseen listener, a subtler performance emerges. She begins to divest herself of her masculine accoutrements, removing her suit's outer shell and surrendering the increasingly fearsome weapons that line its pockets, and her anecdotes take a personal, more revealing turn. With her stories of her traumatic childhood and of the love that brought the gang to a messy end, she betrays a deep-seated fear of exposing her vulnerability and surrendering an inch of the power she strove so ruthlessly to achieve. In these quieter, more introspective moments, MacDonald is captivating, defining the moral nuances of Maggie's louche former lifestyle with finesse.

The Elephant Girls evolves into a deeply psychological struggle between truth and fiction, as Maggie wrestles with the dangerous passion that bubbles beneath her carefully constructed bravado. Complex, subtle, and often deeply uncomfortable, this battle is fascinating to watch.

New Town Theatre, until 28 Aug, 3.30pm, £11 (£9).