Monster is a frustrating play. It certainly tackles an important topic: asking just what it is that drives some men to violence, and whether the essence of that violence lives deep inside us all. And it's clearly a personal catharsis for actor-playwright Joe Sellman-Leava, who tells us at the start of the piece that some of what we're seeing is true. His semi-fictional alter ego, also called Joe, is an actor cast in a brutal and twisted Shakespeare. Eager to please his casually misogynistic director, he embraces his rage-fuelled character, but begins to fear the urges he feels stirring within.

The action takes a while to start, but once Sellman-Leava gets going, he holds our attention throughout. Framed by Joe's story, he channels three very different figures. One's no less than William Shakespeare, represented by quotes from his plays; the next is disgraced boxer Mike Tyson, who speaks openly of his thirst for violence; and the third is Patrick Stewart. Stewart wrote a haunting piece for the Guardian newspaper about his childhood experience of domestic abuse, and Monster quotes extensively from that column – with Sellman-Leava's recreation of Stewart's measured tones offering a startling counterpoint to the power of the words he’s speaking.

These diverse sources are quoted in mashed-up fragments, driven by the semi-fictional Joe's actorly research and earnest debates with his girlfriend. It's a sharp, spare, staccato production, and it's much to Sellman-Leava's credit that he keeps his diverse range of quoted characters so crisply and clearly defined. There's a frisson of danger, the sense of a pressure cooker bubbling away, and director Yaz Al-Shaater has found a particularly striking image for the climax. Yet it's not without humour: from time to time, a witty eye-roll or knowing glance lightens the portentous mood.

The frustration is that, of all the perspectives offered by this play, it's the least well-informed – protagonist Joe's – which is most intricately explored. When Patrick Stewart says he's afraid of roles demanding anger, his words carry dignity and weight; we know a seed was planted in his childhood which he daren't allow to grow. In contrast, while I obviously can't speak for the real Joe Sellman-Leava, the character Joe seems to have enjoyed a peaceful and stable life. So when he makes the same comment, it sounds angsty and self-indulgent – the musings of an actor who's got a touch too obsessed by his part.

And that's why, when Joe turned to his big moral – that violence is a choice – I couldn't help thinking that it's easy for him to say. There's a vital voice missing from Monster: that of a man who, unlike Stewart, emerged from a brutal childhood with a devil inside him, but who somehow, unlike Tyson, found the strength to hold it at bay.

Joe sets out to understand what makes a man a "monster" – yet by the end of the play, all I'd really understood is that being an actor can mess with your mind. It's a strong performance though, neatly put together, and Patrick Stewart's story in particular is well worth hearing. And if it opens up discussion of this difficult subject, in that sense at least it succeeds.