THE CHEMIST SHATTERS the last bottle of vodka over the garbage can, spraying glass and alcohol on his heavy work gloves, a shard bouncing off the facial netting on his helmet. He’s in his greenhouse. It’s dark, quiet. Night is the best time to work, because insect activity is minimal.

He reaches into the glass shards and fishes out the bottle neck, moving with speed and efficiency. He’s getting near the end, a culmination of years of effort. This should be savored. But all of the recent excitement has put him behind schedule, and he has to catch up.

He places the bottle neck on his workbench and uses a hammer and pliers to break all of the glass away from the aluminum cap. When he’s finished, the cap, with its tamper-proof ring along the bottom edge, is intact.

Next he selects an identical brand of vodka, and twists off its top. The tamper-proof ring separates along the perforated line where it is attached to the cap and remains on the bottle neck. He snips the ring off using nail clippers, pours out four ounces of vodka, and adds an equal amount of colorless, odorless ethylene chlorohydrin. It blends invisibly with the liquor.

Then he takes the intact cap-the one he removed from the broken bottle-and carefully screws it onto the full bottle. It now appears to be new, unopened. He places it in the cardboard box next to the eleven other poisoned bottles of alcohol, and gets started on the beer.

Beer is even easier to tamper with. A local brewing supply shop, the same place he got some of his hydroponics equipment, also sells bottle cappers. He carefully pries the tops off of a dozen popular import beer bottles, adds a few drops of conotoxin to each, and then uses the bench capper to reseal the caps until they’re as tight as when they left the brewery.

After finishing a full case of beer, he stands and stretches. There are things that need to be double-checked. He makes sure the Little Otter has a full charge. He lays out the dry suit, places a bottle of talc next to it. Tests the gauge on the nitrox canister.

Then, outside, he changes out of his protective suit and checks the cement mixer, which has another three yards ready. It takes ten minutes to pour. He’s an expert with the forklift, and gets it into place on the first try. Two more to go. He loads the mixer with three more bags. Adds a touch of aluminum. A dash of diesel. A healthy handful of roofing nails.

Inside, he practices for the last time with the TelePC. He’s adjusted for delays. He’s taken the route himself, so the timing should be perfect. This should all work out.

Finally, he uses spell-check on the letter, and prints out a copy.

This will be a nice surprise for Lieutenant Jacqueline Daniels. A beautiful end to a beautiful relationship.

After six years, three months, and thirteen days, Tracey will finally get her revenge.

And then he’ll get his revenge.

AGAINST DOCTOR’S RECOMMENDATION, I checked myself out of the hospital at seven a.m., wearing loaner clothes. A cab took me to my car, which was still in front of the fire hydrant. I drove back to the suburbs, rush hour traffic helping me chase away the groggies.

I felt pretty good, considering. A little weak. A little raw. But ready to work.

Once home, I fed the cat, forced down some oatmeal, hopped into a tepid shower-hot hurt my skin-changed into a pair of boot-cut Levi’s, some Adidas running shoes, and an Anne Klein blouse and jacket-black over white-and called Latham. He was sleeping, but the nurse informed me he was stable. I took that as a good sign.

Next, I climbed in my car and headed back to Chicago. When I got on the expressway, I called Herb.

“Any word on the Hotham file?”

“Missing. That one and the Welch file. From the two-four as well.”

“That’s what I figured. There’s something there the Chemist doesn’t want us to find. What’s the set-up for today?”

“You’ll be carrying a GPS phone, a clone of your cell number. It will track you wherever you go, and has a booster for indoors. They’ve got six cars, two bikes, four teams on foot, and chopper support. You won’t get lost.”

“Any luck finding Tracey’s cell phone, or her car?”

“The Staties found a white Honda in a parking lot in O’Hare. No plates, but the VIN matches. Unlikely they’ll find prints-the car was torched. No ping on the cell phone. They think he’s removing the battery between uses. We’d have to catch him during a call.”

“How about the money?”

“Cash, coins, and stones are all clean, as he demanded. We’ve got the yellow leather suitcase.”

“What’s in it? Radio transmitter? Another GPS?”

Herb didn’t answer.

“Herb?”

“Nothing. There’s nothing in it, Jack. If you run into the Chemist, you’re ordered to stand down. No arrest. No shooting. The mayor doesn’t want to mess with this guy.”

I processed that, but it didn’t get any better the more I thought about it.

“What if I have a chance to catch him?”

“You remember what the loony said if you try.” Herb kicked up his voice to Mickey Mouse level and mimicked, “Many will die, many will die.”

“Many will die anyway. He’s not going to stop.”

“I’m only the messenger,” Herb said. “I don’t like this any more than you do.”

I’m not a person who spits, but I was angry enough to.

“Will you be there?” I asked.

Another pause. Then, “No.”

“Herb-”

“We’re not partners anymore, Jack. I’m not Homicide. I’ve got another case I’m working on.”

“And what case is that?”

“Last week, someone stole a semi full of portable toilets.”

“Well, that’s a lot more important than tracking down the mass murderer who’s terrorizing our city. What do you call that? Grand theft potty?”

“Good-bye, Jack. Be safe.”

Herb hung up.

I had no right to be mad at Herb. The secret to reaching old age in our profession is knowing when to call it quits. If he felt he couldn’t do it anymore, my goading him wouldn’t help either of us.

But Herb was Violent Crimes to the bone. If you cut him, he bled Homicide. Robbery was a waste of his time and talents. He must have known that. He just needed someone to remind him.

I called him back. I was going to open a line of honest communication to get to the bottom of his fears and intentions instead of resorting to blaming and name-calling.

The first words out of my mouth were, “Don’t be an idiot, Herb.”

He hung up on me. I thought about calling his wife, remembered she was in on his silly plan to stay alive until retirement, and instead called Rick.

“I’m glad you called, Jack. I heard about what happened. I wanted to visit you in the hospital, but I figured…” He trailed off.

“No problem. Did you hear what the mayor said?”

“I was at the meeting last night.”

“He wants to give the guy his money without trying to catch him.”

“That’s the plan.”

“You’re not going along with that, are you? The federal government doesn’t make deals with terrorists, right?”

“Not as far as you know.”

“Are you saying-”

“I’m saying that this guy has the means to kill more people. If we pay him off, there’s a good chance he’ll stop. I talked to some special agents on the Behavioral Science Team, and the profiling computer says-”

Great. I’d been down this route several times, and it never led anywhere worth visiting. Was I the only sane cop left in this hemisphere?

I interrupted his profile-speak. “What do you think? You personally?”

“I think he’s got something big planned, and if we bring him in, he’ll let people die.”

“So we just let the guy go?”

“The case won’t be over, Jack. We have a mountain of evidence we haven’t even sifted through. We’ll catch him eventually. And we won’t be risking the lives of civilians.”