10"" as in 10 Downing Street--because this time, in a solid but largely unexciting thriller, the IRA decides to kidnap PM Margaret Thatcher. First-novelist Scott focuses primarily on the edgy IRA team as it plans and executes the scheme: leader Liam Grady, a repressed, puritanical perfectionist; Patrick Farrell, a British Army sergeant with passionately Irish ancestors; Maura Lynch, who has family reasons for hating the PM; and randy, rambunctious Sean O'Sullivan (spurned by Maura). The plan? Well, equipped with UZI firearms from the Iraqi Embassy, the quartet will drive to Whitehall in a stolen London taxi, ambush Thatcher's car (with Maura on sledgehammer), kill her aides, and whisk her off to an abandoned Army barracks in Colchester--thanks to Farrell, who'll also provide Army uniforms and a Land Rover for stage #2 of the getaway. Meanwhile, however, Scotland Yard's Arthur Whitaker has the feeling that some big IRA operation is in the works--especially after he looks into an unexplained murder. (The victim happened to see the IRA team practicing for the kidnap--and was killed by Sean.) So, when the kidnapping does occur, pretty much as planned, Whitaker & Co. are already on the trail, searching for Thatcher while the government wrestles with the IRA demands: total British pull-out from Northern Ireland. . . or death for the PM. And, as the cops close in on the terrorists' hideout, Maura is losing the psychological war with Thatcher--who is simply too cool, brave, and articulate to be intimidated by the usual prisoner-brainwash techniques. Crisply detailed police sleuthing, a few strong action sequences, decent characterization--but only the PM/Maura interplay (which some readers will find too Thatcher-adoring) gives an occasional lift to this penny-plain serving of sturdy, un-clever suspense.