After a promising debut in Drink This, Dewhurst's detective Neil Carter went on to two disappointing, talky sequels. So it's a relief to find a new sleuth here, especially one seemingly headed for brisk, old-fashioned adventure: small-time actress Helen Markham, who specializes in madwomen and is recently estranged from her husband, is recruited by British spymaster Julian Jones to pose as his near-catatonic sister. . . and to infiltrate a Bournemouth nursing-home where KGB agents are dwelling incognito. Unfortunately, however, the ensuing action is more drippy than snappy. Helen, in out-to-lunch guise, sizes up the home's dozen inmates, its staff, looking for signs of duplicity: there's a suicide, a murder, and a mysterious prowler. But Helen, who spends weekends being debriefed by Julian & Co., is a moistly neurotic heroine, mooning verbosely through an identity crisis--especially when it seems that newly beloved Julian (""for whatever reason, a new prospect lay between them, the prospect of opening their arms, moving heart to heart, moving together towards moments,"" etc.) may in fact be a traitor: ""If Julian is prepared to kill me, I'm prepared to die."" None of the fun you might expect from the old amateur-undercover-spy premise; re-read Agatha Christie's N or M? instead.