Boy is waiting for his Humberside family to fall apart. His younger brother Matty is about to be taken away by social services. His mother, mentally ill, is unresponsive, and won't do anything to stop this happening. All that's left is the waiting game, before the silver cars come and take Matty away. That is, until Boy decides he and Matty should take flight. Out into the world beyond.

Niall Ransome (a member of Mischief Theatre, though leaving his comedic chops aside here) has deftly written and directed a one-man piece that rarely pulls its punches, presenting a harrowing portrait of modern Britain. Social care that seems more careless than careful, a faceless series of letters and check-ins. For those on the receiving end, taking flight seems like the only way out. In that respect, FCUK'D shares many qualities with Monsay Whitney's recent Fringe hit Box Clever, the two modern plays giving voices to those normally deprived of them.

The similarities don't end there, with both pieces also using subtle and quirky choices of form. While Box Clever had its dual protagonists, here it is the beat poetry rhythms of Ransome's script that embellish the piece with a neat lyricism and an innate meter that ticks over. When Boy and Matty end up being chased through the night by police, the flashing lights become 'blue and black panic attacks'. It's almost an extended Larkin poem, revamped and retasked to suit the 21st century.

Crucially though this choice of style never feels forced, largely because of the central, powerhouse performance from Will Mytum. There is masterful characterisation at work, and Mytum is capable of making us both sympathise for this optimistic, driven figure while never letting us forget how young and flawed he still is. 'I want every day to be better', Boy declares brightly at the show's opening. He is a naif in an unforgiving world. Mytum bounds across the stage, giving the story its relevant gusto and pace. This energy is interrupted one too many times by the show's quieter moments, with Ransome as director giving his lead performer so many brooding pauses that they mean the audience begin to disengage.

A vital component of the experience is Peter Wilson's score, an unsettling beast that is reminiscent of the thrumming and unorthodox textures that you'd find in the work of the likes of BAFTA-winner Cristobal Tapia de Veer. It runs alongside Boy, following and embellishing his experiences as he journeys further and further from home. Jess Bernberg's lighting is subtle, its use of blue washes and occasional yellow tinges creating a neat atmosphere. Grace Venning's set, with its street lights and painted basketball court, constantly reminding us of Boy's childishness and urban upbringing.

It's an assured first play for Ransome, and it'll be interesting to see where the writer goes next. Compared to the dazzling lights of pantomime (or even the cavalcade of fun mere metres from the Bunker at the Menier), this is a timely and pertinent hour of theatre. As the programme notes remind us, over 100,000 children run away from home every year. That's no small amount.

FCUK'D runs at the Bunker until 30 December.