She played mind games with herself to fill the long empty hours. She floated down endless ski runs through perfect crystalline air. She performed difficult surgeries and reread all her dreary medical school textbooks. She spoke often to her mother. But it was the moment of her capture she thought of most. It played ceaselessly in her memory, like a loop of videotape over which she had no control: the men in black jumpsuits pouring out of the vans, the shredded bodies of her friends lying in Hyde Park, the man who had tried to save her. She had glimpsed him briefly as they were forcing her into the back of the van, an angular figure with gray temples, crouched on one knee with a gun in his outstretched hands. She wondered often who he was. She hoped that one day, if she were ever rescued, she would have an opportunity to thank him.

If she were ever rescued… For some reason she found it easier to contemplate her own death than to picture the moment of her liberation. She knew that she was almost certainly the target of a massive search, but her hope of ever being found faded as the days ground slowly past—and as the notes came with a mind-deadening regularity. Do you want food?…Do you wish to use the toilet?… But on the fifth day, as the man with gray temples was boarding a jetliner at Heathrow Airport, a different note appeared. It said: One of my men needs a doctor. Will you help us? “Yes,” she replied in a low voice, and a moment later Cain and Abel entered her cell and lifted her gently to her feet.

They led her wordlessly up a flight of steep narrow stairs, slowly, so that she did not trip over the shackles. At the top of the stairs they passed through a creaking metal door and entered a small warehouse. It was abandoned and dark, except for a single utility lamp burning above a cluster of cots in the far corner. On one of the cots lay a man whose face was not covered by a balaclava. It was twisted into a grimace of pain and damp with sweat. Cain lifted the blanket, exposing his right leg.

“Jesus Christ,” Elizabeth said softly.

The bullet had entered below the knee and had shattered the crown of the tibia. The entrance wound was about two centimeters in diameter and was imbedded with bits of debris from the clothing he had been wearing the morning of the attack. The surrounding skin was now reddish brown and badly swollen, and red streaks had begun to radiate up the thigh. It was obvious he was suffering from a severe local infection and was on the verge of sepsis. She reached toward his wrist, but one of the terrorists seized her arm. It was the one with brown eyes: Cain.

“I have to take his pulse.”