"Who the hell are you?" Benjamin Stern's rude question to the intruder in his apartment was answered quickly by an equally rude -- and fatal -- bullet. This is only the first shot in The Confessor, Daniel Silva's rapidly thrusting thriller. This adroitly plotted, multilayered novel features Gabriel Allon, the ex-Mossad operative art restorer who held us enthralled in The Kill Artist and The English Assassin.