A play set in the world of pop/rock music might seem to be very much boys’ fare. While there’s enough here to keep the most overgrown lad engrossed (Gosh, is that a Gibson guitar? Yes, and just as that legendary instrument-making company files for bankruptcy protection), Mood Music is about a woman’s fight to secure due credit for her work.

Cat is a talented musician, paired by her record company with experienced hitmaker Bernard. He has overreached his role as producer, reworking her songs, taking formal joint credit which becomes de facto sole credit, because he’s him: famous, arrogant and male. We plunge into the deep end with each explaining the situation to her/his own psychotherapist, then lawyers enter to argue out Cat’s claim for full songwriting credit and against shameful treatment meted out to her on the road.

Joe Penhall couldn’t write an unintelligent play if he tried, and sometimes he’s so sharp, so smart that that’s thrilling in itself. His breakthrough play Blue/Orange was one example; Mood Music inhabits broadly similar territory by using the process of psychotherapy as a means of uncovering broader and deeper issues, and it’s just as electrifyingly smart. We see not just into Cat’s and Bernard’s backgrounds but the paradoxical way the whole business is set up, to trade emotional honesty and connection as mass-produced goods. Above all, commercial success provides a literal get-out-of-jail-free card. Bernard’s combination of entitlement and insecurity is toxic and ends up polluting Cat, but at its heart is the sexual stereotyping that pervades music more than many other areas: the assumption that she creates the feelings, but he fashions the work.

Ben Chaplin is magnificently loathsome as Bernard, entirely casual about neither knowing nor caring what he’s done to Cat. His only outright emotional outburst is when one of his piano chords gets called hackneyed. (The snatches of music are plausible and detailed, by James Bond soundtrack maestro David Arnold.) Seána Kerslake’s Cat is all Dublin directness, but seemingly given the runaround by everybody at one time or another. Jemma Redgrave is solicitous as her shrink, Pip Carter long-suffering as Bernard’s; similarly, Kurt Egyiawan is assiduous as Cat’s lawyer while Neil Stuke as his opposite number spouts more bull than a Fray Bentos production line.

So many subjects at once... It could so easily be an almighty mess, or get so bound up in the minutiae of the biz that it doesn’t reach across the footlights. But Penhall’s clever, agile writing and Roger Michell’s production, which keeps all the characters almost constantly on the move around the thrust stage, make things lively and compelling from start to finish.

Written for The Lady.