The Moonstone meets Black Sunday in this tale of terrorists plotting to bomb the New York auction of a fabled diamond. Ilsa Nachtigal--just released from a German prison and determined to avenge her dead husband by attacking the widow of the politican whose bill executed him--learns that the widow, grasping Baroness Helene von Brandenburg, is putting the 85-carat Malabar Angel up for auction under the auspices of newcomer Charles Luttrell's Burnaby's auction house. Ilsa enlists the services of former IRA mechanic Frank Hermon to accompany her overseas to the Park Plaza Hotel and plant an explosive timed to blow in the ceiling of the Grand Ballroom at the climactic moment. Meanwhile, gentle London-based Father Gerard Vaughan, egged on by Luttrell's wife-in-name-only Lucy, is trying to recover the diamond for the Indian Diocese of Malabar--from which the stone was taken centuries ago--either by purchase or lawsuit; pushy tabloid-journalist Victoria Stewart-Robinson threatens to jam the carefully orchestrated publicity campaign that's drawn sharp-eyed bidders from Tokyo (the Acanthus Museum) to Hollywood (faded star Gloria Grace); and Craig Clifford, the Park Plaza's straight-arrow Assistant Director of Security, starts a romance with junior manager Barbara Andrews that's sure to endanger his shaky marriage--even as he begins to close in on the mysterious honeymoon couple in Room 538. . . . Forgettable characters and dollops of soap opera still don't defuse the tried-and-true suspense formula that Cox (The Botticelli Madonna, Hartman's Game) manipulates like the sturdy veteran he is.