A Code Only We Knew
二人だけの暗号
The slip carried a five-letter group and a name Hale did not recognise at first.
The letters, however, followed a that only he and Lena had ever used.
Years ago they had built a private code, a game of lovers who trusted no one.
What the code now spelled out was the of the man selling London's secrets.
Decoded, the letters gave a : the traitor's working name in Soviet files was "Frost."
What mattered was not the name itself but the small clues hidden inside its use.
Provided that Lena had told the truth, Frost had been for at least three years.
Unless Hale could tie the to a real face, the paper proved nothing at all.
He spent two days in the eastern library, reading old newspapers for the meetings Frost had attended.
What he needed was a : a man always present when secrets went missing.
Slowly, a shape emerged from the dates, a shadow that fit one officer disturbingly well.
Provided that his reasoning held, the traitor was someone he had known for many years.
Yet a good trap is built from exactly what the victim most wants to believe.
What if Lena had chosen a name that would turn him against an innocent ?
Unless he tested the information, he might become the weapon that removed her real enemy.
He decided to check the against a fact that only the true Frost could know.
He sent a harmless message through an old , containing a small, error.
If Frost were the man he suspected, the error would come back to him, quietly corrected.
Three days later the corrected version reached him, exactly as he had darkly predicted.
What returned was , not of Lena's honesty, but of the traitor's careful, invisible .
Provided that he read the signs correctly, the man called Frost sat two desks from his own.
It was a who had shaken his hand at his wedding and mourned at his father's grave.
Hale felt no , only the cold weight of what such certainty would cost him.
Unless he could carry hard back to London, no one would believe a hunted man.
And what London wanted, he knew, was not the truth but a story that could be closed.
He folded Lena's slip into his shoe and began, at last, to plan his way home.