Marino sat up, squinting groggily at me. It was time for breakfast and cigarettes, not necessarily in that order.
The dining car was half filled with semicomatose clientele who could have been sitting in any bus station in America and looked very much at home. A young man dozed to the beat of whatever was playing inside the headphones he wore. A tired woman held a squirming baby. An older couple was playing cards. We found an empty table in a corner, and I lit up while Marino went to see about food. The only positive thing I could say about the prepackaged ham and egg sandwich he came back with was that it was hot. The coffee wasn’t bad.
He tore open cellophane with his teeth and eyed the shopping bag I had placed next to me on the seat. Inside it was the Styrofoam box containing samples of Sterling Harper’s liver, tubes of her blood, and her gastric contents, packed in dry ice.
“How long before it thaws?” he asked.
“We’ll get there in plenty of time, providing we don’t make any detours/’ I replied.
“Speaking of plenty of time, that’s exactly what we got on our hands. You mind going over it again, the bit about this cough syrup shit? I was half asleep when you were rattling on about it last night.”
“Yes, half asleep just like you are this morning.”
“Don’t you ever get tired?”
“I’m so tired, Marino, I’m not sure I’m going to live.”
“Well, you better live. I sure as hell ain’t delivering those pieces an’ parts by myself,” he said, reaching for his coffee.
I explained with the deliberation of a taped lecture. ‘The active ingredient in the cough suppressant we found in Miss Harper’s bathroom is dextromethorphan, an analogue of codeine.
Dextromethorphan is benign unless you ingest a tremendous dose. It’s the d-isomer of a compound, the name of which won’t mean anything to you–”
“Oh, yeah? How do you know it won’t mean nothing to me?”
“Three-methoxy-N-methylmorphinan.”
“You’re right. Don’t mean a damn thing to me.”
I went on, “There’s another drug which is the 1-isomer of this same compound that dextromethorphan is the d-isomer of. The 1-isomer compound is levomethorphan, a potent narcotic about five times stronger than morphine. And the only difference between the two drugs as far as detection goes is that, when viewed through an optical rotatory device called a polarimeter, dextromethorphan rotates light to the right, and levomethorphan rotates light to the left.”
“In other words, without this contraption you can’t tell the difference between the two drugs,”
Marino concluded.
“Not in tox tests routinely done,” I answered. “Levomethorphan comes up as dextromethorphan because the compounds are the same. The only discernible difference is they bend light in opposite directions, just as d-sucrose and 1-sucrose bend light in opposite directions even though they’re both structurally the same disaccharide. D-sucrose is table sugar. L-sucrose has no nutritional value to humans.”
“I’m not sure I get it,” Marino said, rubbing his eyes. “How can compounds be the same but different?”
“Think of dextromethorphan and levomethorphan as identical twins,” I said. “They’re not the same people, so to speak, but they look the same–except one is right-handed, the other left-handed. One is benign, the other strong enough to kill. Does that help?”
“Yeah, I guess. So how much of this levomethorphan stuff would it take for Miss Harper to snuff herself?”
“Thirty milligrams would probably do it. Fifteen two-milligram tablets, in other words,” I answered. “What then, saying she did?”
“She would very quickly slip into a deep narcosis and die.”
– *
“You think she would’ve known about this isomer stuff?”
“She might have,” I replied. “We know she had cancer, and we also suspect she wanted to disguise her suicide, perhaps explaining the melted plastic in the fireplace and the ashes of whatever else it was she burned right before she died. It’s possible she deliberately left the bottle of cough syrup out to throw us off track. After seeing that, I wasn’t surprised when dextromethorphan came up in her tox.”
Miss Harper had no living relatives, very few friends –if any–and she didn’t strike me as someone who traveled very often. After discovering she had recently made a trip to Baltimore, the first thing that came to mind was Johns Hopkins, which has one of the finest oncology clinics in the world. A couple of quick calls confirmed that Miss Harper had made periodic visits to Hopkins for blood and bone marrow workups, a routine relating to a disease she obviously had been quite secretive about.