Blend Jack the Ripper and Sherlock Holmes with Dracula lore, toss in a copious complement of czarist Russian history, and the result is Carole Nelson Douglas"s Castle Rouge, her grisly but gripping sequel to 2001"s Chapel Noir. Disaster has struck opera diva-turned-detective Irene Adler Norton. The American adventuress who bested Holmes and thereby won his admiration (in "A Scandal in Bohemia") thought she"d cornered the elusive Ripper on the grounds of the 1889 world"s fair in Paris, but instead, he fled to Eastern Europe after kidnapping her friend and biographer, Penelope "Nell" Huxleigh. Now, while Irene--assisted by theatrical manager Bram Stoker, daredevil Yankee reporter Nellie "Pink" Bly, and British spy Quentin Stanhope--sets out for Prague, hoping to rescue Nell, and as Holmes and Dr. John Watson revisit Saucy Jack"s earlier homicidal activities in London, Nell finds herself imprisoned, together with Irene"s barrister husband, in a crumbling Transylvanian castle, under the malevolent scrutiny of a Russian woman agent and a brutish lust-murderer endowed with hypnotic powers. Douglas builds considerable intrigue on her way to a surprising solution to the Ripper"s identity. Yet it"s unfortunate that this sixth Irene Adler yarn focuses more on the prudish Nell and her discomforts as a hostage (no proper corsets-- how shocking!) than on its more intrepid chief protagonist, or even on Pink, whose capacity for audacious exploits was better realized in Chapel Noir. Regrettable, too, is the plot"s shift from Paris to the eldritch extremes of Bohemia. Stoker points out that "the region reeks with bizarre legend and folktales," yet Castle Rouge"s action takes place well apart from the Gypsy villages that might have provided cultural color. --J. Kingston Pierce