"LITERATE AND SAVVY ... BRIMS WITH WARTIME INTRIGUE. "--The Washington Post Book WorldEngland 1943. Much of the infamous Nazi Enigma code has been cracked. But Shark, the impenetrable operational cipher used by Nazi U-boats, has masked the Germans' movements, allowing them to destroy a record number of Allied vessels. Feeling that the blood of Allied sailors is on their hands, a top-secret team of British cryptographers works feverishly around the clock to break Shark. And when brilliant mathematician Tom Jericho succeeds, it is the stuff of legend... "A TENSE AND THOUGHTFUL THRILLER. "--San Francisco ChronicleUntil the unthinkable happens: the Germans have somehow learned that Shark has been cracked. And they've changed the code... "SUSPENSEFUL AND FASCINATING. "--The Orlando SentinelAs an Allied convoy crosses the U-boat infested North Atlantic ... as Jericho's ex-lover Claire disappears amid accusations that she is a Nazi collaborator ... as Jericho strains his last resources to break Shark again, he cannot escape the ultimate truth: There is a traitor among them... "GRIPPING ... CAPTIVATING . "--New York Daily News"ELEGANTLY RESEARCHED ... Readers will find themselves perfectly placed to experience one of Britain's finest hours. "--People"SATISFYING ... Harris does a crackerjack job here, playing his characters' lives off historical events in surprising ways. "--Entertainment Weekly"SUSPENSEFUL ... FIENDISHLY CLEVER. "--Detroit Free Press