Religious discontent, royal excess, labyrinthine espionage and a terrorist atrocity make this a cut above the average historical crime novel.

It's almost like an episode of Spooks with clandestine meetings, undercover missions, codes, threats, betrayals, kidnappings and close-quarter fights.

It's superior to Gregory's long-running Matthew Bartholomew whodunnit series and is the best of her five books featuring 17th Century spy Thomas Chaloner.

The experienced agent is the reluctant employee of the Earl of Clarendon, the Lord Chancellor and confidante of the recently restored King Charles II.

The Earl has reached new heights of unpopularity after giving his name to the Clarendon Code, which outlaws any worship other than Church of England.

London has become a seething mass of complainants, plotters and potential rebels from both the Roman Catholic and Puritan camps.

Chaloner is following Blue Dick, just one of many possible revolutionaries, when the religious zealot is killed in front of him.

His investigations centre on the inhabitants of the bridge, but take him into both the slums and the mansions of London's aristocracy.

Somewhere there's a connection between missing fireworks, the bones of Thomas Becket, Chaloner's former spymaster, and the rape of the wife of a bridge clerk.

A Murder on London Bridge has many characters, each with their own motives and leanings, and has a many-faceted plot.

But Gregory expertly keeps everything clear through almost 500 pages of intrigue and action.

The result is not quite as gripping as CJ Sansom's Tudor mysteries but -- in the absence of a new book from him for two years -- this is quite a page-turner.

David Knights