Excerpt from A Spy Among Friends by Ben Macintyre, plus links to reviews, author biography & more

The admiration of his subordinates was echoed by the approbation of Philby's superiors. Felix Cowgill called him "a good cricket umpire." There could be no higher praise. Here was a man who played by the most honorable rules. But some saw a flicker of something else in Philby, something harder and deeper, a "calculating ambition," a ruthless "single-mindedness." Like Elliott, he used humor to deflect inquiry. "There was something mysterious about him," wrote Trevor-Roper. "He never engaged you in serious conversation—it was always irony."

As head of the Iberian section, Philby faced a formidable challenge. Although Spain and Portugal were officially neutral noncombatants in the war, in reality both countries tolerated, and even actively encouraged, German espionage on a grand scale. Wilhelm Leissner, the Abwehr chief in Spain, presided over a well-funded, sprawling intelligence network made up of more than two hundred officers (more than half the German diplomatic presence), with some fifteen hundred agents deployed around the country. Leissner's principal target was Britain: recruiting and dispatching spies to the UK, bugging the British embassy, bribing Spanish officials, and sabotaging British shipping. Portugal was another hotbed of espionage, although Abwehr operations were less efficient under the command of a dissolute German aristocrat named Ludovico von Karsthoff. The Abwehr poured spies and cash into Spain and Portugal, but in his duel with Leissner and Karsthoff, Philby had one overwhelming advantage: Bletchley Park, the top secret decoding station where intercepted German wireless messages were decrypted, furnishing a priceless insight into Nazi intelligence. "It was not long before we had a very full picture of the Abwehr in the Peninsula," wrote Philby. That information would soon be put "to good use in disrupting, or at least seriously embarrassing, the enemy on his own chosen ground."

Nicholas Elliott's task of attacking German intelligence in the Netherlands, his former stomping ground, was a different proposition, and even harder. The Abwehr in Nazi-occupied Holland was highly effective, recruiting, training, and dispatching a stream of spies to Britain. By contrast, infiltrating agents into Holland was exceptionally difficult. The few networks that had survived the Venlo incident were riddled with Nazi informers.

In a plot that smacks of James Bond (and has all the hallmarks of an Elliott ruse), a Dutch agent named Peter Tazelaar was put ashore near the seafront casino at Scheveningen, wearing full evening dress and covered with a rubber suit to keep him dry. Once ashore, Tazelaar peeled off his outer suit and began to "mingle with the crowd on the front" in his dinner jacket, which had been sprinkled with brandy to reinforce the "party-goer's image." Formally dressed and alcoholically perfumed, Tazelaar successfully made it past the German guards and picked up a radio previously dropped by parachute. The echo of 007 may not be coincidental: among the young blades of British intelligence at this time was a young officer in naval intelligence named Ian Fleming, the future author of the James Bond books. Ian Fleming and Nicholas Elliott had both experienced the trauma of being educated at Durnford School; they became close friends.

Peter Tazelaar was one of the few to make it back to Britain. Of the fifteen agents sent into Holland between June 1940 and December 1941, only four survived, thanks to the brutal efficiency of Major Hermann Giskes, the head of Abwehr counterintelligence in Holland, Elliott's opposite number. In August 1941 Giskes intercepted a team of Dutch SOE agents shipped into Holland by fast Section V 33 torpedo boat and forced them, under threat of execution, to send encrypted wireless messages back to Britain, luring more spies across the water. Some fifty-five Dutch agents were subsequently captured and dozens executed, in a Double Cross operation code-named Englandspiel ("The England Game"), before two managed to escape and alert the British to the fact that they were being hoaxed. Winding up the operation, Giskes sent a final, mocking wireless message: "This is the last time you are trying to make business in Netherlands without our assistance Stop we think this rather unfair in view our long and successful co-operation as your sole agents Stop but never mind whenever you will come to pay a visit to the Continent you may be assured that you will be received with the same care and result as all those who you sent us before Stop so long." The episode was "an operational disaster," in Philby's words, but almost equally alarming was the discovery that German intelligence in Holland had managed to slip at least one spy into Britain undetected.

Excerpted from A Spy Among Friends by Ben Macintyre. Copyright © 2014 by Ben Macintyre. Excerpted by permission of Crown. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.