But Sarah Monteiro wasn’t thinking clearly. The best escape was the first one she could find, even if its destination was the gates of hell. Anything was better than getting caught by an unknown organization apparently worse than the worst of those she knew about.

Sarah bought a one-day travel card at a self-serve machine. This would allow her to move freely the whole day within the 274 stations in the 250 miles of underground trains. Whoever wanted to follow her would have a tough job and need a lot of luck.

Even so, she couldn’t relax. Ultimately they would be able to determine her point of departure. And in due time, they could also pinpoint her destination. Her father had scared her with his description of the organization dogging her. Was he exaggerating? How long would it take them to find and capture her?

While trying to figure out what kind of dangerous documents had fallen into her hands, she decided to run the risk. There was no other choice.

Sarah slid her transit card into the turnstile, which opened, then closed behind her. There was no turning back. She had selected the District and Circle lines, and fate would decide the rest. She went down the stairs to the tracks. In two minutes there would be a Circle Line train to Tower Hill. And another, to Upminster, would reach the station in three; that one was on the District Line, one of the city’s longest and oldest, open to the public since the nineteenth century.

At that point, the trains on either side arrived and departed parallel to each other, which allowed passengers on both sides to see the other platform across the tracks. A train going to Wimbledon had just arrived on the other side.

There were only a handful of people on Sarah’s platform. An older man was reading the Times, and two young women chatted excitedly, constantly interrupting each other.

The train on the opposite track pulled out. Sarah noticed the red lights as the train entered the dark tunnel on its way to Wimbledon. Looking at the train schedule, she saw that in one minute a train that could save her would open its doors. A cold gust of wind, out of nowhere, chilled her bones, making her situation even more uncomfortable. She was tired and sleepy, but her intense dread overwhelmed everything else. Being used to eight hours’ sleep every day, she would have to pay for this when it was all over. Lack of sleep made her cranky, as her colleagues in the pressroom knew well. But escaping was her only thought now. She was unaware that her pursuers had at their disposal technology so sophisticated that any of her movements, such as paying for a hamburger, making a call from public phone, or buying a transit card would immediately be identified, sounding an alarm.

A rumble in the back of Sarah’s mind brought her back to reality. At the far end of the tunnel where she had seen the lights turn red for a departing train, she now saw yellow lights, growing bigger and bigger. Her train was coming.

The doors opened to let passengers out. Only a few people were in the car. One young kid was sprawled out, sleeping.

Two men had just arrived on the platform on the other side, apparently executives. Something about their attitude, however, made them seem suspicious. They were nervously looking all around. Watching them, Sarah, motionless in her car, sank down in her seat, trying to disappear from view. The executives were consulting a piece of paper, perhaps the photo of someone they were after. By sheer luck, they were on the other side and didn’t see her.

“Shut the damned doors and let’s go,” Sarah mumbled, mentally addressing the conductor.

Repeated chimes warned that the doors were about to close. A few seconds later, the train was picking up speed toward Tower Hill. Sarah sighed, relieved, and once her long train was inside the tunnel, she straightened up in her seat. She had never imagined that she could enjoy the monotonous clatter of a train so much.

Through the glass doors, Sarah observed the people in other cars. In the one just behind her, she saw two men and a woman. A teenager was watching a movie on a portable DVD player.

And then she saw him. He was wearing a dark suit, similar to the other two in Victoria Station. He was standing, comparing Sarah’s face with a photo he was holding. It was obvious he had just recognized her.

Putting his index finger to his lips, he motioned her to be silent, and started moving toward her. Sarah also moved, but in the opposite direction, running toward the front of the train. She hastily opened the door between the two cars. The other passengers noticed her opening and closing doors, but took no interest.

The train started to brake as it entered Saint James’s Park Station. The man was looking for anything that could tell him the whereabouts of the woman he was after, who had disappeared into the first cars.

For Sarah it all took an instant, her fright provoking a tremendous burst of adrenaline. Her strength seemed to multiply, following her instinct to escape. She curled up on the floor, wedged against seats that faced the door, waiting. In a second, she hurtled out of the car onto the platform and started running as fast as she could.

The man resembling the two other executive types quickly jumped out of the train and saw Sarah getting away, three cars ahead. Trying to run after her wasn’t worth the effort. So he pulled out his gun and aimed with professional skill. A smile of recognition crossed his face: what an easy target.

The man pulled the trigger. At the same moment, Sarah jumped into one of the cars, and the bullet was swallowed by the darkness of the tunnel.

He had to get back on the train immediately, but the doors had already closed and the train was in motion. When the train finally left the Saint James’s Park Station, the man grimaced. Seconds later he mumbled something, his hand near his mouth.

Still in shock and with tears streaming down her cheeks, Sarah didn’t dare look at the other passengers. The train stopped again. As soon as the doors opened, she bolted out.