Prisoners, Lovers, & Spies

From parlor trick to weapon of war, invisibleink and other means of hidden writing emerge as one of mankind's moreintriguing inventions in this lively history.Georgia Tech history professor Macrakis (Seducedby Secrets, 2008) surveys2,000 years of secret messages penned with an improbable variety of substancesand methods: lemon juice, various bodily fluids and other liquids that dry invisiblyon the page but turn brown when exposed to heat. Gall-nut extract, forinstance, a traditional ink used by George Washington's agents, turns blackwhen brushed with iron sulfate, and cobalt solutions painted on fire screens blossominto brilliant green foliage when warmed. Some modern inks require fourdifferent chemical treatments to develop; an invisible ink invented by LinusPauling shows up only when treated with a specific antibody. Aside fromchemical compounds, microdots can cram pages of documents into a tiny spot thesize of the period at the end of this sentence, and digital encoding techniquesallow messages to be inserted into Internet porn. Macrakis offers lucidexplanations of the chemistry and optics underlying the seemingly magicalproperties of invisible inks, and she even appends recipes that guide readersin making some of the simpler varieties. The heart of her book, though, is thecat-and-mouse game between spies who conceal their reports in plain sight andcounterintelligence officials trying to intercept and detect them, a saga shefollows from the subterfuges of Mary Queen of Scots to dueling Cold Warintelligence agencies. Her chronicle luxuriates in colorful characters-Jesuitsplotting to escape from the Tower of London, James Bond-ianplayboy-spies and Mata Hari-like femmes fatales-and intricate cloak-and-daggerfeaturing inks secreted in fake molars and infused into garments. It's also astory of government surveillance at a level that would make Edward Snowdencringe: During the world wars, Britain and theU.S. opened millions of letters and testedthem for invisible messages. Macrakis unearths a wealth of information, including secret documents she mined from East Germany'sStasi archives, weaving it together with engaging prose that illuminates a seldom-seenaspect of espionage.An engrossing study of unseen writing and thepicaresque misadventures of those who employ it. COPYRIGHT(1) Kirkus Reviews, ALL RIGHTS RESERVED.