“What?” I move to her side of the Map and look at the spot she’s pinpointing with her finger.

“This doesn’t make any sense,” she says. “That set of shelves has all the X-whatevers except X Sigma. There’s no X Sigma anything anywhere.”

Leaning in for a closer view, I see she’s right. How weird is that? The label lists everything that starts with X plus a letter from the Latin alphabet.

I scan the Map again. There are no call numbers with Greek letters. But the second letter of the call number is definitely a ∑. A Sigma.

Maybe the note was a typo.

“You will not find Chi Sigma on the Map.”

Nicole and I both spin around. I don’t know about Nicole, but my heart is racing. I feel like we got caught sneaking into school after dark, not searching for a library book.

Standing right behind us is the librarian, Mrs. Philipoulos. I adore her—she helped me find obscure Aristotle writings for my final in Mr. Dorcas’s philosophy class—but she scares me a little. She is no stereotypical librarian. She only comes up to my chin, making her maybe five foot. Maybe. My best guess at her age is seventy, but you wouldn’t know it from how she’s dressed. It’s not every day you see a five-foot, seventy-year-old librarian wearing black cargo pants and a black leather corset top. And certainly not one that looks good in that outfit.

“Mrs. Philipoulos,” Nicole gasps. “You scared the Hades out of us.”

“We librarians have to be stealthy.” She shrugs her tiny shoulders. “How else can we expect to spy on young lovers in the stacks?”

My cheeks flush with the memory of one night during finals week when Griffin and I slipped down the modern-dramatic-theory aisle for a make-out session, certain that no one in their right mind would come looking for one of those books. We quadruple-checked that no one was around. There was no way she could have—

“Mrs. Philipoulos!” I gasp.

The tiny librarian winks at me.

I give her a weak smile.

Remembering why we’re here—and desperate to deflect my embarrassment—I ask, “Why won’t we find Chi Sigma on the Map?”

Why didn’t we guess that the X was really a chi?

“Because,” she says, her ruby-glossed lips smiling mischievously, “that is one of the secret collections.”

“Secret collections?” I repeat. Why would someone send me a call number for a book in a secret collection?

“One of?” Nicole gasps. “You mean there’s more than one?”

“Of course, dear.” Mrs. Philipoulos turns sharply and walks to her desk.

“She’s a little scary,” I whisper.

Nicole whispers back, “She’s a descendant of Nemesis.”

Who is that? I shake my head.

“Goddess of retribution,” Nicole explains.

I’m impressed. “No wonder she looks like she can kick butt.”

“She also has excellent hearing,” Mrs. Philipoulos says as we reach her desk. Before we can react, she says, “What is the exact call number, dear?”

As I read it out she quickly keys in the letters and numbers.

“Interesting,” Mrs. Philipoulos says, squinting at the screen. Her short, spiky gray hair glows blue in the light from her flat-panel monitor.

“What?” Nicole and I both ask, hurrying around the desk to see.

Mrs. Philipoulos presses a red button on her keyboard and the screen goes blank just as we catch a glimpse.

“I’m sorry, girls,” she explains, “but that segment of the collection is off-limits to students.”

“What do you mean?” I ask. “Isn’t this a student library?”

“Of course.” She gives me a sad look. “But we are also the official archival library of Mount Olympus.”

“So?” Nicole asks, defiantly crossing her arms over her chest.

“So,” Mrs. Philipoulos replies, just as defiantly, “not every document the gods file is fit for student eyes.”

My shoulders slump. After all the racing my brain has done since I got that note, I half expected some kind of miracle in that call number. I’m not sure what kind of miracle, but I was sure there was some kind of mystery about my dad’s death that might explain why he’d died. Why he’d done it. Why he’d decided that his football career was the most important thing in his life. Some clue to how I might avoid the same fate.

Now I might never know.

“That’s all right, Mrs. Philipoulos,” I say, defeated. “Thanks for your help.”

Nicole gapes at me. “What?” she asks. “You’re giving up? When you’re this close”—she holds up her palms half an inch apart—“to finding the truth?”

“What truth?” I throw back. “My dad died. The gods smoted him because he abused his powers to succeed in football. Nothing can change that.”

“How can you be—”

Mrs. Philipoulos gasps, stopping Nicole midsentence. “You’re Nicky Castro’s daughter.”

“Did you know my dad?”

“No, not personally.” She gives me a sad, sympathetic smile. “But I knew of him.” After a thick beat, she adds, “Everyone did.”

My eyes water. There’s something in that beat, in that silence, that tells me the entire hematheos world knows Dad’s story. Like he’s a warning. Careful how you use your powers or this will happen to you.