“Sonia,” Cady said. “She used to babysit me, can you believe that? Why they tortured her, not to mention me, by making her do it, I have no idea. She used to go on about my mom, how she saw her with Matt at the Diamond Duck—that doesn’t exist anymore. It used to be a bar on Massachusetts Street.

“‘He looked miserable,’ she’d say, ‘trapped. You could tell he didn’t want to be with her, but he had such exquisite good manners, he wouldn’t tell her to go away.’ Finally, one day when I was about six or seven, Gram overheard her and told her never to come back. I asked who Sonia was talking about, and she said Sonia couldn’t tell truth from imagination if it hit her with a two-by-four and Gram should never have let Dr. Kiel push her into hiring Sonia. I guess Sonia couldn’t hold down any kind of job, and the Kiels wanted her out of the house.

“Of course, my whole life I’ve wondered. But whenever I’d ask Gram, she’d shut me up—pretty much like she was hitting me with a two-by-four. Well, you saw her the other night.”

She poured herself another splash of wine. “‘Why you would want the most incompetent student who ever walked into Dr. Kiel’s lab to be your father is beyond me.’ Then I’d ask who it really was and she’d say, ‘I don’t know, punkin,’ and that would be the end of it. I wish you had real proof. Or do you, and you’re just not telling me, like every other goddamn person in Lawrence old enough to know?”

“I really don’t know,” I said gently. “Unless we can find his DNA, or his family, or something about him, I don’t think you’ll ever prove it either.”

Cady’s mouth twisted in a guilty smile. “When I was a teenager, I snuck into the microbiology department office—Gram was still working for Dr. Kiel, and I’d sometimes go up there after school. Anyway, she was off doing something, so I went and looked at the microbiology-student files. I wanted to find Matt Chastain’s home address. I had this plan where I was going to borrow the car and drive to wherever his family lived.”

She blushed. “I saw the whole scene, me interrupting the family at dinner. ‘Where’s my daddy?’ I’d cry, and then, while they were all flabbergasted, I’d announce who I was. I’ve never told this to a single soul, not even my best friends, because it sounds so crazy, something Sonia Kiel would do, not sober, reliable Cady Perec.”

She laughed with embarrassment and turned her head aside.

“I take it you never went?” I asked.