John Stanley’s gritty debut play The Monkey, one of the winners of Synergy Theatre Project’s national prison scriptwriting competition, is a fast-moving, plain-talking black comedy that somehow manages to be very funny and incredibly grim all at once. Directed by Russell Bolam, it’s an honest portrayal of a world that’s often violent and unforgiving, but drawn with the sympathetic pen of a writer who knows his subject matter well, and tackles head-on the stereotype that says just because people find themselves in a bad situation, it doesn’t necessarily mean they’re bad people.

The action begins in the stairwell of a run-down block of flats in Bermondsey. This is the home of petty criminals Dal (Daniel Kendrick) and Becks (Danielle Flett), and their nice but dim local drug dealer Thick-Al (George Whitehead). Life’s not exactly easy for the trio, but it’s also fairly uneventful… until Dal’s childhood friend Tel (Morgan Watkins) comes back into town to retrieve £500 he lent Thick-Al in an unlikely moment of generosity. Realising he’s been taken for a mug, the unpredictable Tel, who’s never been quite the same since falling on his head during a robbery a few years ago, sets out to take his bloody revenge – and woe betide anyone who gets in his way.

What’s so appealing about The Monkey is that despite everything that goes on (and between the language and the violence, it does get pretty graphic at times), all the characters – even the psychotic Tel – have redeeming features and are even quite likeable. There’s genuine friendship on display here, for instance, even if it is expressed through liberal use of the c-word, and in many ways the characters’ idiosyncrasies make them easier to get along with: Tel and Thick-Al’s shared love of Jaffa Cakes is oddly endearing, as is Tel’s unexpected obsession with cleanliness.

This flawed humanity is captured in four brilliant performances from the cast. Morgan Watkins is particularly enjoyable as Tel, a ticking time bomb of twitchy, pent-up energy that occasionally explodes in bursts of violent rage towards anyone who happens to be nearby. Impeccably dressed in suit and tie, Tel stands out from the Bermondsey crowd, and his air of superiority shows that he’s well aware of the fact, while his admiration for Tarantino’s Reservoir Dogs exposes him as a frustrated gangster wannabe.

At the opposite end of the scale, George Whitehead’s affable and appropriately named Thick-Al has no such pretensions, and is so laid-back he’s practically horizontal; content to lounge about on the sofa all day, all he cares about is his next fix, and he’s blissfully unaware of the trouble he’s in until it’s too late. Daniel Kendrick and Danielle Flett fall somewhere in between the two as Dal and Becks – while they’re quite content to get on with life in the only way they know, they are at least alert to the danger posed by Tel’s return and its potential ramifications, not just for Al but for themselves as well.

Not for the fainthearted, The Monkey is nonetheless a thoroughly enjoyable 90 minutes (and educational: not only did I learn some new rhyming slang, I now know that Tim Roth’s from Dulwich, not Deptford – yes, I did go away and look it up) with larger than life, complex characters who feel like real people, not clichés. It’s an impressive debut from John Stanley and well worth checking out during its short run at Theatre503.