"Rich kid with a gonzo bank account or his parents," he said. "Mr. and Mrs. Deep Pockets pony up for tutoring, then toss in a whole bunch more for someone to take the test for Junior because it's all about getting Junior into Harvard and Junior can't hack it on his own. The ringer aces the test, Junior buys himself a crimson sweater, everyone's over the moon. Then Elise hits 'em up for a serious surcharge. But if it's only one kid, why three dates?"

"Once could've been the general SAT," I said, "the others the SAT IIs--achievement tests on specific subjects."

"We cover all your needs at the Academy of Scam."

"If we're talking big-time extortion, that could explain abandoning the rape plot. This was so much easier and Elise would keep her job."

He got up, stretched, sat down. "With the stakes so high, how'd our tipster find out? And why be so cryptic?"

"Maybe a hardworking kid picked up on an unlikely score by another student and got resentful. Peer pressure would frown on snitching publicly, you'd be sentencing yourself to high school hell. And by exposing a scandal you'd be putting everyone at Prep at risk of taint, including yourself."

"I'm not really a rat, I'm just giving the cops a hint. They don't figure it out, it's their fault. Wonder what those ethical seminars they run at Prep would say about that."

He laughed. Turned serious. "Maybe Marty Mendoza's our tipster. He'd sure be p.o.'d watching some rich brat pay for a high score."

"Maybe," I said. "Though I'd think Marty would have less trouble being explicit. And something else: The basics of the scam could be right but the murder motive could be different. Not protection from blackmail, snuffing out the competition. Because the drive from Fidella's house to Sierra Madre runs right through Pasadena. And someone lives there who'd be a perfect ringer."

He stared at me. "Trey Franck."

"Brilliant, Prep alumnus, looks young enough to pass for a high school student, changes his hair color regularly."

"Not a hipster thing, a goddamn disguise. Does the grunt work and takes all the risk, gets tired of Elise and Fidella pocketing the big bucks."

"He's the one who directed you to Marty. We have only his word that Elise was scared of Marty. If that was a diversionary tactic, it worked."

"Oh, man." He shot up again, stomped into the hall, returned flushed. "I'm getting that itchy feeling, like I've been played. The whole Marty thing steered us away from Franck's relationship with Elise. All along you've been saying Elise's murder stank of calculation and brains. Franck's a chemical engineer, claims he hasn't worked with dry ice since he was a little kid but so what? Nothing adds fun to homicide better than a little nostalgia, right?"