The Illegals. By Shaun Walker. Knopf; 448 pages; $32. Profile Books; £22

The Mission. By Tim Weiner. Mariner Books; 464 pages; $35. William Collins; £25

The Spy in the Archive. By Gordon Corera. Pegasus Books; 336 pages; $29.95. William Collins; £25

TO BE AN intelligence officer is to make sacrifices: to wear a mask, to deceive even those close to you, to persuade others to betray their countries. When answering the call of duty, some have to make greater sacrifices than others. In the early 1970s Yury Linov reported to a KGB clinic in Moscow, where he was circumcised. Mr Linov then headed for Israel, where he introduced himself as Karl-Bernd Motl, an Austrian Jew. The real Mr Motl was alive and well, living in East Germany. Mr Linov was a KGB "illegal"—an intelligence officer operating not only under a false name, but also a false nationality.

His remarkable story is told by Shaun Walker, a journalist, in "The Illegals", one of the most compelling and insightful books on intelligence of the past decade. It is one of a trio of new works, alongside Gordon Corera's "The Spy in the Archive" and Tim Weiner's "The Mission", which illustrate the foibles of different spy agencies: Russia's obsession with illegals and America's reliance on firepower at the turn of the millennium.

In the 1920s Soviet leaders feared that foreign powers would try to bring down their regime. They knew this was possible, since they had only recently helped overthrow the regimes that came before them. So they created some fake plots to smoke out counter-revolutionaries. Yakov Blyumkin, one illegal, pretended to be a Persian merchant, selling religious manuscripts stolen from Ukraine. Georgy Agabekov posed as an Armenian carpet salesman. There was a fishmonger in Paris and a bookseller in The Hague.

Many intelligence officers pose as diplomats, but use their real names. Illegals, by contrast, must speak, act and even think like a native. Slips are inevitable. Iosif Grigulevich—an illegal who attempted to assassinate Leon Trotsky, a revolutionary—was once asked at an exhibition whether he liked Marc Chagall's paintings. "Nyet," he replied,...