"Not helping." I sit in her desk chair and read the note aloud again.

"What was that last bit?" she asks.

"X Sigma 597.11 FL76." It makes no sense. It's not even a word. "What is it? Some kind of code or something?"

"It seems familiar," she says.

Nicole jumps up and grabs a scrap of paper and a pencil with a skull-and-crossbones eraser at the end. Handing them to me, she says, "Write it out. Exactly as it is in the note."

When I do, she claps her hands. "I know what that is!"

"You do?"

"Yes." She smiles triumphantly. "It's a call number. Like from the library."

A call number? I shake my head.

"It's a book!"

"Oh," I say brilliantly. A book. How is some book supposed to explain something about my dad? It's not like just anyone can publish stuff about the secret world of the gods. Mount Olympus totally has supernatural protections against that kind of thing. Why would this crazy note have a library call num-

"What are you waiting for?" Nicole demands, grabbing me by the wrist and pulling me to the door. "Let's go to the library."

I've never seen Nicole get so excited about anything-except that time she came up with the plan to help me capture and then break Griffin's heart. That time didn't turn out so well for me. She temporarily zapped away my ankle muscles so Griff would have to carry me home. That was before they made up, of course. And before he and I got together.

It was the thrill of strategy and espionage that excited her then. It's a good bet that it's the same thrill that has her hurrying me across the campus lawn. In under two minutes we've made it from her room to the library door.

I'd been to the library dozens of times during the school year. Researching a book-length term paper for Ms. T's lit class. Using the computer lab to check out a supercool 3-D physics simulator program in Ms. Madrianos' class. Looking up newspaper accounts of my dad's death.

Still, as Nicole and I walk through the glass double doors, I can't help staring in awe.

You know what most high-school libraries are like? Small, cramped, and with so few books that if every student checked one out at once, the shelves would be empty? Well the Academy library is so not like that.

First of all, it's huge.When you walk in, you're on the second story, on a balcony that overlooks the basement-level main floor. Circling the upper level is an alternating pattern of tables and chairs, individual study carrels, and comfy armchairs facing low coffee tables. Who wouldn't want to study in here?

Second of all, it's beautiful.There is light everywhere on the balcony and pouring into the open space below. Since it's at the corner of the school, it has two full walls of windows that let in glorious sun all day. The shelves that line the balcony are the exact same color as the Academy exterior, so they blend right in with the walls. Everything is trimmed in gold-I have a feeling it's realgold-and marble. All the fabrics are this gorgeous gold swirly-girly pattern. As far as lush interiors go, it could rival any of the great palaces of the world.

Third of all, it's full of books.Oh, not so much that you feel crowded by them or anything, but if they had a card catalog-which they haven't since computerizing everything in the nineties-it would be the size of an average high-school library. Almost all of the books are in the basement level, which spreads out under the entire school. Probably farther. This is totally the kind of place that would have secret chambers or hidden passages or something else right out of a Nancy Drew novel.

"Come on," Nicole calls out as she heads for the sweeping staircase that leads to the lower level. "Let's check the call number against the Map."

Note clutched in my hand, I hurry after her. The Map is a huge-scale, Plexiglas floor plan of the library that details what's on every shelf. Not to the book, of course-wouldn't that be cool, though, if it was some ultra hip, interactive map where you could scan through every book on the shelf!-but by call number.

When we reach the map I unfold the note and read the call number out.

"X Sigma 597.11 FL76." I'm sure that makes sense to somebody-librarians, probably-but to me it's just a garble of numbers and letters.

The one bad thing about the Academy library is that nothing is in order. At least, not call-number order. Or any other order, as far as I can see. Tracing over the Map with our fingers, Nicole and I search every inch of it. I'm just about to give up, when she says, "Here it is." Followed immediately by, "No, that's not it."

"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 exceptX 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 Greekletters. But the second letter of the call number is definitely a Ј. 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 sec a five-foot, seventy-year-old librarian wearing black cargo pants and a black leather corset top. And certainly not one that looks goodin 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.