That evening, she arrived home to her small flat in Tufnell Park. She hung her tweed coat on a hook, removed her felt hat, and sat at a cluttered desk. Under a loose floorboard was a state-of-the-art satellite phone.

For forty years, Eleanor Rigby had taken the Northern Line. She knew every rattle, every flicker of the fluorescent lights, and every unspoken rule. Don’t make eye contact. Don’t smile. Clutch your bag. Survive.

"First time?" Eleanor asked.