Policeman Baz Vartis longs for detective work and the chance to carry a firearm. But the only kit he's issued with is a Tactical Mountain Bicycle in order to join Britain's growing new breed of biking Bobbies.

While battling both the absurdities of politically correct policing and criminals who see him as fair game for ridicule and assaults, at home his main fight is with his overbearing, alcoholic mother Bernice who keeps him in her unhealthy grasp, even soaping him clean at bath time.

He'd like to forge a relationship with Val Stone, a formidable cycling WPC, but impotency fears combine with the feeling that he dare not walk out on his crazy mum.

Just before riots and disorder break out on the streets of London, a head injury inflicted by a gang causes a seismic shift in Baz's persona. He becomes a vigilante cop who kills according to strict rules: criminals caught within certain postcodes are offered the choice of arrest or death.

Starting with the gang leader who attacked him, Baz embarks on a reign of terror, in which the lack of protestations by criminals too stunned, confused, or drunk to argue when he asks, "May I kill you?" are taken as consent by Baz, who dispatches them in a number of unique ways. And those he apprehends and metes out justice to are all filmed on his helmet-cam.

Posting the footage on social networks, Baz builds up thousands of fans for each killing and, with simple precautions, keeps his identity anonymous and untraceable. At last, the cycling bobby who was a figure of fun and such a disappointment to his mum is now an all-powerful phenomenon, dispensing justice to assorted lowlifes and scumbags, in his view for the greater good. He even receives praise on social networks.

Soon, however, the deepening urge to apply his singular brand of law and order leads to shorter and shorter intervals between killings. Then Baz's private life turns precarious. Val finds herself falling in love with him. And Maya, a trafficked waif whom Baz rescues in a white slave bust, is brought into the ménage at home, sending mother Bernice into a jealous spin.

Baz's nemesis arrives in the form of Seth, a rough thief with low esteem who tracks him down. Seth wrongly believes Baz has murdered his rich, eccentric aunt Mags and stolen his inheritance. Bursting into Baz's home he discovers that his quarry is the vigilante killer whom he had hitherto been a fan of on Twitter. Suddenly Seth, a failure in everything he has ever done, is in thrall to the mighty legend that is Baz Vartis.

Then things get really messy...

May I Kill You? screenings: 11th - 17th January 2013 at Prince Charles Cinema, Leicester Square.