Since his death in 1972, there has been an increasing fascination with Hoover and the immense power he wielded as director of the FBI. Although there have been two recent major biographies--Athan G. Theoharis's The Boss ( LJ 6/1/88) and Richard G. Powers's Secrecy and Power ( LJ 2/1/87)--this massive new study promises to be the most extensive and controversial yet. Gentry, who coauthored Helter Skelter ( LJ 11/15/74), has based his account of Hoover on more than 300 interviews and on access to previously classified FBI documents.