Never leave the shelter of your home or workplace without having your car key in hand. Walk to your vehicle with the key protruding from between your curled fingers like a shank. Do not unlock the door if a stranger is standing behind you. Do not climb into the car without first checking the backseat. Once inside, keep the doors locked at all times; if you need air, a window may be cracked one inch.

My father did not believe in weapons; he had read that women were more likely to lose possession of their firearm and have it used against them. That's why until the age of fourteen I wore a whistle around my neck for use in case of emergency and always carried mace.

That year, however, I knocked out my first opponent in a juniors sparring contest at the local gym. I had given up karate in favor of kickboxing, and it turned out I was quite good at it. The assembled crowd was horrified. The mother of the boy I flattened called me a monster.

My father took me out for ice cream and told me I'd done good. "Not that I'm condoning violence, mind you. But if you're ever threatened, Cindy, don't hold back. You're strong, you're fast, you have a fighter's instinct. Hit first, question later. You can never be too prepared."

My father entered me in more tournaments. Where I honed my skills, learned to focus my rage. I am fast. I am strong. I do have a fighter's instinct. It all went well until I started winning too much, which of course garnered unwanted attention.

No more tournaments. No more life.

Eventually, I would throw the words back in my father's face: "Prepared? What's the use of being so prepared when all we ever do is run away!"

"Yes, sweetheart," my father would explain tirelessly "But we can run because we are so prepared."

I HEADED FOR the Boston Police Department straight from my morning shift at Starbucks. Departing Faneuil Hall, I had only a one block walk to the T, where I could catch the Orange Line to Ruggles Street. I had done my homework the night before and dressed accordingly: low-slung, broken-down jeans, frayed cuffs dragging against the pavement. A thin chocolate-colored tank top layered over a black, tight-fitting long-sleeve cotton top. A multicolored scarf of chocolate, black, white, pink, and blue tied around my waist. An oversize blue-flowered April Cornell bag slung over my shoulder.

I left my hair down, dark strands falling halfway to my waist, while giant silver hoops swung from my ears. I could, and had on occasion, pass as Hispanic. I thought that look might be safer for where I would be spending my afternoon.

State Street was hopping as usual. I tossed my token into the slot, breezed my way down the stairs to the wonderful, rich, urinal smell that accompanied any subway station. The crowd was typical Boston-black, Asian, Hispanic, white, rich, old, poor, professional, working-class, gangbanger, all milling about in a colorful urban tableau. Liberals loved this crap. Most of us simply wished we could win the lottery and buy ourselves a car.

I identified an elderly lady, moving slowly with a teenage granddaughter in tow. I stood next to them, just far enough away not to intrude, but close enough to seem part of the group. We all regarded the far wall studiously, everyone careful to avoid one another's eyes.

When the subway car finally arrived, we pressed forward as one cohesive mass, squeezing into the metal tube. Then the doors shut with a whoosh and the car hurtled into the tunnels.

For this leg of the trip, there weren't enough seats. I stood, holding a metal pole. A black kid wearing a red headband, oversize sweatshirt, and baggy jeans gave up his seat for the elderly woman. She told him thank you. He said nothing at all.

I shifted from side to side, eyes on the color-coded transit map above the door, while I did my subtle best to appraise the space.

Older Asian man, working-class, to my far right. Sitting, head down, shoulders slumped. Someone just trying to get through the day. The elderly woman had been given the seat next to him, her granddaughter standing guard. Then came four black male teens, wearing the official gangbangers' uniform. Their shoulders swayed in rhythm with the subway car, as they sat, eyes on the floor, not saying a word.

Behind me a woman with two small kids. Woman appeared Hispanic, the six- and eight-year-old kids white. Probably a nanny, taking her young charges to the park.

Two teenage girls next to her, both decked out in urban chic, hair in braids, oversize diamond studs winking from their ears. I didn't turn but pegged them as worth keeping on radar. Girls are more unpredictable than boys, thus more dangerous. Males posture; females have a tendency to get straight in your face, then when you don't back down, start slashing away with concealed knives.

I wasn't too worried about the girls, though; they were the known unknowns. It's the unknown unknowns that can knock you on your ass.

The Ruggles Street stop arrived without incident. Doors opened, I departed. No one spared me a second glance.

I hefted my bag over my shoulder and headed for the stairs.

I'd never been to the new police headquarters in Roxbury. I'd only heard the stories of midnight shootings in the parking lot, of people being mugged outside the front doors. Apparently, the new location had been some political bid to gentrify Roxbury, or at least make it safer at night. From what I'd read online, it didn't seem to be working.

I kept my bag tucked tight to my side and walked on the balls of my feet, ready for any sudden movement. The Ruggles Street station was large, crowded, and dank. I wove my way swiftly through the mass of humanity. Appear purposeful and focused. Just because you're lost is no reason to look that way

Outside the station, down a steep flight of stairs, I spotted the towering radio antennae to my right and took the hint. Just as I headed down the sidewalk, however, a sneering voice yelled from behind me, "Looking good, Taco! Wanna try a burrito with real meat?"

I turned, spotted a trio of African American boys, and flipped them off. They just laughed. The leader, who looked about thirteen, grabbed his crotch. Now it was my turn to laugh.

That took some of the thunder out of them. I twisted back around and headed up the street, footsteps calm and even. I clenched my hands into fists so they wouldn't tremble.

BPD headquarters was hard to miss. For one thing, it was a vast, glass-and-metal structure plopped down in the middle of crumbling brown housing projects. For another, concrete barricades were positioned all around the front entrance, as if the building were actually located in downtown Baghdad. Homeland security, brought to every government building near you.

My footsteps faltered for the first time. Since I'd decided what I was going to do last night, I hadn't allowed myself to think about it. I'd planned. I'd acted. Now here I was.

I put my bag down. Drew out a corduroy blazer the color of milk chocolate and put it on, the best I could do to dress myself up. Not that it mattered. I had no proof. The detectives would simply believe me or not.

Inside, there was a line in front of the metal detector. The officer in charge demanded to see my driver's license. He inspected my oversize bag. Then he looked me up and down in a manner that was supposed to inspire me to say, Yes, I'm secretly smuggling guns/bombs/drugs into police headquarters. I had nothing to say, so he let me through.

At the front desk, I drew out the newspaper article, checking once more for the detective's name, though in all honesty, I knew it by heart.

"Is she expecting you?" the uniformed officer asked me with a stern frown. He was a hefty guy with a thick mustache. Immediately, I thought of Dennis Franz.

"No."