Bletchley Park on a cloudy night did not look like the sort of place where one might save the world. A few lights reflected in the lake and gave a slight glow to the facade of the Victorian pile that constituted the main house, but the rest of the place looked shabby and uninspiring. Long, low buildings with all the architectural distinctiveness of a garden shed sprawled out in every direction, reminding Patton of the temporary classrooms at Alta Vista High School. Some had been restored—but the structures were so unadorned and utilitarian, it was hard to tell the renovated ones from the derelict ones. In the eerie illumination of the occasional security light, it was hardly the sort of place to make the heart soar with pride and amazement at the achievements of a great generation.

But Patton’s heart did soar. For a few minutes, as they wandered the grounds, careful to keep an eye out for any night watchmen, she forgot all about Fritz and Franz and sniper bullets and her assassin cum traveling companion and listened to the voices of the past. Here Dilly Knox developed the “rodding” technique to help break Enigma messages. Here Mavis Batey broke the Italian Enigma and decrypted messages that helped the Allies succeed in the D-Day landings. Here Alan Turing and Gordon Welchman created the Bombe—the machine that became a bridge between human intelligence and the computer age, a machine whose only purpose was to break Enigma. It had succeeded spectacularly. Perhaps most amazingly, all this work had remained secret. Despite thousands of people working at Bletchley at the height of the war, no one outside the gates had the slightest idea what went on there. The Germans believed until the very end that Enigma remained unbroken, and with the Official Secrets Act demanding silence on the part of all who had worked there, Bletchley’s invaluable contribution to the war had remained a secret until the mid-1970s.

“I can’t believe I’m walking in the footsteps of Alan Turing,” said Patton as they made their way past one low building after another. “It’s all a museum now, you know. I wish we could go in and—”

“Listen,” said Nemo, “I appreciate that this is some sort of pilgrimage for you, but in case you didn’t notice, another car pulled up to the gate just after we did. A car with its headlights off.”

“We’re being followed?” said Patton.

“Yes,” said Nemo, “and I don’t think it’s by some fellow Alan Turing enthusiast. Now let’s get on with the job at hand before we come face-to-face with good old Fritz and Franz.”

“You think it’s them?”

“Them or somebody just as dangerous,” said Nemo. “Where is this friend of yours?”

“This way,” said Patton, pointing to a sign reading “National Museum of Computing.”