Passenger number four was wearing a black canvas messenger bag, urban style, looped in front of one shoulder and behind the other, and hauled around into her lap. The way the stiff fabric bulged and sagged made it look empty apart from a single heavy item.

The train stopped at 28th Street. The doors opened. No one got on. No one got off. The doors closed and the train moved on.

Point eleven: hands in the bag.

Twenty years ago point eleven was a recent addition. Previously the list had ended at point ten. But things evolve. Action, and then reaction. Israeli security forces and some brave members of the public had adopted a new tactic. If your suspicions were aroused, you didn’t run. No point, really. You can’t run faster than shrapnel. What you did instead was grab the suspect in a desperate bear hug. You pinned their arms to their sides. You stopped them reaching the button. Several attacks were prevented that way. Many lives were saved. But the bombers learned. Now they are taught to keep their thumbs on the button at all times, to make the bear hug irrelevant. The button is in the bag, next to the battery. Hence, hands in the bag.

Passenger number four had her hands in her bag. The flap was bunched and creased between her wrists.

The train stopped at 33rd Street. The doors opened. No one got off. A lone passenger on the platform hesitated and then stepped to her right and entered the next car. I turned and looked through the little window behind my head and saw her take a seat close to me. Two stainless bulkheads, and the coupler space. I wanted to wave her away. She might survive at the other end of her car. But I didn’t wave. We had no eye contact and she would have ignored me anyway. I know New York. Crazy gestures on late night trains carry no credibility.

The doors stayed open a beat longer than normal. For a mad second I thought of trying to shepherd everyone out. But I didn’t. It would have been a comedy. Surprise, incomprehension, maybe language barriers. I wasn’t sure that I knew the Spanish word for bomb. Bomba, maybe. Or was that light bulb? A crazy guy ranting about light bulbs wasn’t going to help anyone.

No, light bulb was bombilla, I thought.

Maybe.

Possibly.

But certainly I didn’t know any Balkan languages. And I didn’t know any West African dialects. Although maybe the woman in the dress spoke French. Some of West Africa is francophone. And I speak French. Une bombe. La femme là-bas a une bombe sous son manteau. The woman over there has a bomb under her coat. The woman in the dress might understand. Or she might get the message some other way and simply follow us out.

If she woke up in time. If she opened her eyes.

In the end I just stayed in my seat.

The doors closed.

The train moved on.

I stared at passenger number four. Pictured her slim pale thumb on the hidden button. The button probably came from Radio Shack. An innocent component, for a hobby. Probably cost a buck and a half. I pictured a tangle of wires, red and black, taped and crimped and clamped. A thick detonator cord, exiting the bag, tucked under her coat, connecting twelve or twenty blasting caps in a long lethal parallel ladder. Electricity moves close to the speed of light. Dynamite is unbelievably powerful. In a closed environment like a subway car the pressure wave alone would crush us all to paste. The nails and the ball bearings would be entirely gratuitous. Like bullets against ice cream. Very little of us would survive. Bone fragments, maybe, the size of grape pits. Possibly the stirrup and the anvil from the inner ear might survive intact. They are the smallest bones in the human body and therefore statistically the most likely to be missed by the shrapnel cloud.

I stared at the woman. No way of approaching her. I was thirty feet away. Her thumb was already on the button. Cheap brass contacts were maybe an eighth of an inch apart, that tiny gap perhaps narrowing and widening fractionally and rhythmically as her heart beat and her arm trembled.

She was good to go, and I wasn’t.

The train rocked onward, with its characteristic symphony of sounds. The howl of rushing air in the tunnel, the thump and clatter of the expansion joints under the iron rims, the scrape of the current collector against the live rail, the whine of the motors, the sequential squeals as the cars lurched one after the other through curves and the wheel flanges bit down.

Where was she going? What did the 6 train pass under? Could a building be brought down by a human bomb? I thought not. So what big crowds were still assembled after two o’clock in the morning? Not many. Nightclubs, maybe, but we had already left most of them behind, and she wouldn’t get past a velvet rope anyway.

I stared on at her.

Too hard.

She felt it.

She turned her head, slowly, smoothly, like a preprogrammed movement.

She stared right back at me.

Our eyes met

Her face changed.

She knew I knew.

WE LOOKED STRAIGHT AT EACH OTIIER FOR THE BEST part of ten seconds. Then I got to my feet. Braced against the motion and took a step. I would be killed thirty feet away, no question. I couldn’t get any deader by being any closer. I passed the Hispanic woman on my left. Passed the guy in the NBA shirt on my right. Passed the West African woman on my left. Her eyes were still closed. I handed myself from one grab bar to the next, left and right, swaying. Passenger number four stared at me all the way, frightened, panting, muttering. Her hands stayed in her bag.

I stopped six feet from her.

I said, ‘I really want to be wrong about this.’

She didn’t reply. Her lips moved. Her hands moved under the thick black canvas. The large object in her bag shifted slightly.

I said, ‘I need to see your hands.’

She didn’t reply.

‘I’m a cop,’ I lied. ‘I can help you.’

She didn’t reply.

I said, ‘We can talk.’

She didn’t reply.

I let go of the grab bars and dropped my hands to my sides. It made me smaller. Less threatening. Just a guy. I stood as still as the moving train would let me. I did nothing. I had no option. She would need a split second. I would need more than that. Except that there was absolutely nothing I could do. I could have grabbed her bag and tried to tear it away from her. But it was looped around her body and its strap was a wide band of tightly woven cotton. The same knit as a fire hose. It was pre-washed and pre-aged and pre-distressed like new stuff is now but it would still be very strong. I would have ended up jerking her up off her seat and dumping her down on the floor.

Except that I wouldn’t have gotten anywhere near her. She would have hit the button before my hand was halfway there.

I could have tried to jerk the bag upward and swipe behind it with my other hand to rip the detonator cord out of its terminals. Except that for the sake of her easy movement there would be enough spare length in the cord that I would have needed to haul it through a giant two-foot arc before I met any resistance. By which time she would have hit the button, if only in involuntary shock.

I could have grabbed at her jacket and tried to tear some other wires loose. But there were fat pockets of goose feathers between me and the wires. A slippery nylon shell. No touch, no feel.

No hope.

I could have tried to incapacitate her. Hit her hard in the head, knock her out, one punch, instantaneous. But as fast as I still am, a decent swing from six feet away would have taken most of half a second. She had to move the ball of her thumb an eighth of an inch.

She would have gotten there first.

I asked, ‘Can I sit down? Next to you?’

She said, ‘No, stay away from me.’