The Dying Light, By Henry Porter

"Governments these days – they are run either by gangsters or spooks," the Prime Minister's spokesman laments in The Dying Light. "Merrie old England" only five years hence: a country sliding inexorably towards "a shitty little dictatorship". Henry Porter's future Britain is a place where a "corrupt cabal" about the PM is capable of exploiting the insouciance of press and public to engineer nothing short of a police state. Impossible? Not if you accept that the necessary laws to "dismantle democracy and the rule of law overnight" exist on the statute book.

Porter's story begins at the inquest into the death of a former head of the Joint Intelligence Committee, David Eyam, presumed to have lost his life in a terrorist bomb attack in Colombia. His former lover, Kate Lockhart – now a high-powered New York lawyer – is in court as film of his last moments are picked over by the coroner. Although they were estranged, in the minutes before the explosion he rang and left a message seeking a rapprochement.

At his funeral an old friend rises from his pew to denounce the government. When Lockhart learns the contents of Eyam's will, it becomes clear he is challenging her to piece together the truth of his fall and his last years in the wilderness. It is a dangerous legacy because the PM, John Temple, will use all the powers of "the database state" to track his enemies and suppress the truth - even if it means sanctioning murder and something close to martial law.

Porter's well-regarded thriller, Brandenburg, was set in the days before the fall of the Berlin Wall in a society edging towards the light of freedom. He describes The Dying Light as a a mirror image – of a society that still has recognisably democratic institutions, free courts and media, but is "ineluctably drawn towards the night".

Eyam is an outlaw, a Robin Hood for our times – "the database slayer" in a country where cameras and computers record every detail of life, a crusader for civil liberties against executive powers. At its best The Dying Light bowls along at a cracking pace with more twists and turns then the street map of Venice. It is well written and researched, with a rich cast of characters. But the voice of the columnist intrudes too often to hammer home the message. Characters serve the polemical purpose – a PM who has sold his "dark soul", a corrupt businessman obsessed with Napoleon, an "information systems creep". The story is driven by a dystopian vision of a Britain where all the checks and balances have been pushed aside – in particular cabinet government and parliamentary scrutiny. The Dying Light is a fascinating challenge to be ever-vigilant – a call to "fight what is going on" - but will it have the prophetic power to shock the reader?

Andrew Williams's novel 'The Interrogator' is published by John Murray