A thriller for real

At Risk (Hutchinson, £12.99)

Stella Rimington was, of course, the first female director-general of MI5, and the first holder of the post to become a public figure.

Her autobiography, Open Secret, which came out a few years ago, is perhaps overburdened with trivia - the costumes, for instance, she and her husband wore when they won the fancy-dress competition on the liner taking them to India (she went as the lion, he as the unicorn).

Nevertheless, it is interesting on MI5's recent history, sensible on questions of security, and discouraging on the difficulty, even impossibility of reconciling such an exigent post with marriage and motherhood.

Her early years with the service were less stressful: finding the investigation of communist conspiracies in rural Sussex a far from onerous task, she'd while away the time by reading Dornford Yates thrillers under her desk.

At Risk, her first attempt at the genre, is realistic where Yates is romantic, and its style owes more to civil service memoranda than to Yates's quasi-Biblical sonorities, but it is no less well plotted, and no less compellingly readable than his novels.

Dame Stella's heroine, Liz Carlyle, has fine brown hair, an oval face and "sage-green eyes", and works in the counter-terrorism section of MI5. Wiser than her creator, Liz is unmarried, and breaks off relationships the moment they begin to intrude on her work.

Indeed, she's just in the process of dumping Mark, who wants to make their liaison permanent, when, at a meeting of the Joint Counter-Terrorist Group, MI6 comes up with the rumour that one of the Islamic terrorist groups is infiltrating an "invisible" - CIA-speak for an ethnic native of the country concerned - into the UK.

The plot takes off, and we follow both hunters and hunted - the narrative, daringly, uses multiple points of view - until they come together in a bloody denouement on the cricket field of a Norfolk village.

As might be expected, the Security Service background is exceedingly convincing, and the author is amusing on the relationship between MI5 and 6: the former considering the latter unsound, meretricious and flashy, exemplified here by Liz's counterpart, Bruno Mackay, with his Savile Row suits and Kilroy-Silk perma-tan.

Mostly the action takes place in the rural wastes of north Norfolk, an area Dame Stella obviously knows well, and which she describes with feeling. Though the plot has perhaps a twist too many, and one wishes that advice had been sought on Russian transliteration and translation, At Risk is a beguiling and successful debut.