Transferring to the West End after a successful debut on Broadway, TheMotherfucker with the Hat is a play that had everyone talking – for obvious reasons. As rebellious and expletive-ridden as its title, this strikingly contemporary story by Stephen Adly Guirgis explores the theme of addiction in 21st century society. But beneath its apparently sensationalist title, the play proves to be a thought-provoking reflection on the nature and integrity of human relationships.

The characters in The Motherfucker with the Hat are all entangled in a corrupt web of sexual infidelity and drug addiction. The main protagonist, Jackie, is a former drug dealer who has just been released from prison, and is clean – but his girlfriend Veronica is a secret cocaine addict, and his ex-alcoholic parole counsellor, Ralph, has been sleeping with her behind his back. It is when Jackie spies the eponymous hat belonging to Ralph in Veronica’s flat that all hypocrisy breaks loose, and as he consults his cousin Julio on how to take revenge, we cut to the play’s key questions.

Central to the conflict between Jackie and Ralph appears to be the issue of moral relativism. While Ralph has achieved sobriety, Jackie still struggles to restrain his self-destructive urges; but crucially, unlike Ralph, whose clean image becomes a facade for the worst kinds of deception, Jackie is a character genuinely motivated by something purer. ‘I didn’t get clean to live like that,’ Jackie shouts – and indeed, it is the hot-headed ex-criminal who emerges as the hero of the story.

The play is particularly well-constructed to deliver its message. Despite initially playing out as a comedy, we’re suddenly taken aback by a drastic change in tone: from a bawdy melodrama between Jackie and Veronica, we descend rather sentimentally into their ill-fated love story. The play is in fact a very serious and contemplative one – even the ceaseless exchange of swear words carries the rhythmic, melodic quality of a Shakespearean verse – ultimately reminding us that infidelity and addiction are not a game.

The cast all excel at carving a kind of human sympathy out of their flawed characters. Ricardo Chavira’s heartfelt portrayal of Jackie as a wronged man misguidedly trying to do right helps to make the final blow of the play even more touching. But it is the performance of Yul Vasquez as Jackie’s cousin Julio which is most memorable: a body-building, loyalty-prizing, sex-addicted masseur, his character is an utterly unique invention, and brings some of the most light-hearted moments of the play.

Don’t be fooled by the title of the play: if you think you know what you’re in for, you’re probably wrong. The Motherfucker with the Hat is just as endearing as it is subversive, just as refreshing as it is daring: beneath all of the profundities is something remarkably profound, and I’m glad the National Theatre took the risk in staging it to a British audience.