INVESTIGATIONS: The Secret Life of Clifford Irving

THE grand jury was sending out subpoenas like invitations to an enormous masked ball, with an improbable guest list, ranging from ex-convicts to publishing executives to members of Author Clifford Irving's sometimes exotic circle on the Balearic island of Ibiza. The Howard Hughes affair was turning into a still more absorbing drama, with among other things an emotionally fascinating subplot of adultery. The unmasking of the plot would come soon, it seemed—perhaps this week. When it does, Irving confided cryptically to a friend in Manhattan, "you'll be amazed at how simple...