“Looks like both samples probably came from the same person,” Sullivan said. “They’re almost exactly the same. My DNA tech tells me there’s a small variation, but it’s a level of variation you’d see only with identical twins.”

“Identical twins?” Troy said, the words feeling like stones in his mouth.

“Crazy, right? Not sure how much you work with genetics, Doc, but I do a little reading on this stuff ‘cause of my job. Identical twins, adult twins, don’t have the exact same DNA like we used to think they did. They mutate, you know? Diet, lifestyle, environment—those things can alter someone’s genetic profile over time. They’d still be pretty damned close, obviously, but not a hundred percent match.”

Troy pulled into the parking lot of a gas station and nosed his sedan into a parking space near the corner. He stared out the windshield, but he kept seeing Grace’s face.

“Anyway, it’s gotta be a mistake,” Sullivan said.

Troy didn’t respond. He knew there was no mistake.

But identical twins? No way. Grace was old.

How old did she look last night, when she was working me over like a high-priced hooker?

The memory made his arms break out in gooseflesh.

It also forced him to question, anew, his perceptions of the woman. Grace had certainly looked old when he’d first encountered her at Lily’s funeral, like any reasonably attractive older woman trying to conceal her age with artfully applied makeup. But more recently, such as that morning, when he’d caught her nearly naked in her bedroom, she didn’t look a day past thirty.

She looked, in fact, as if she could have been Monica’s twin, didn’t she?

“You there, Doc?” Sullivan asked.

Grace had obviously drugged him last night. She had apparently drugged his mother, too, and he was increasingly convinced that she was doping up Monica to gain her continued compliance. But he wondered if Grace’s scheming ran to an even more insidious level.

What if Grace wasn’t Monica’s mother at all?

What if she was really her twin? What if she’d been deceiving them from the start with a combination of makeup and wigs?

It was a far-fetched possibility, but their lives had become so crazy that he was willing to entertain almost anything.

“Did I lose you, Doc?” Sullivan asked.

“I didn’t screw up the samples,” Troy finally said. “But this variation in the DNA—what else can you tell me about that?”

“Funny you ask,” Sullivan said. “There was a weird thing with a small percentage of the mother’s sample.”

“What weird thing?”

“The lab couldn’t determine what it was.”

“It wasn’t in their database?” Troy asked.

“Foreign material, they called it.” Sullivan chuckled.

Troy didn’t laugh. He felt cold, though heat blew from the air vents surrounding him. Foreign material? How could that be possible?