Robert Ludlum, who died recently, was a master at the conspiracy theory type of thriller, his books operating on an ever-spiralling series of surprise revelations, with double, treble and quadruple crosses as everyday as sun-ups and sunsets. This last effort is as up to scratch as the other 22 he left behind him, in its tale of the devious workings of the intelligence agency known as "The Directorate". Great value at £12.99, or you could always wait for the television mini-series.
Protect and Defend, by Richard North Patterson. Hutchinson, £9.99 in