Olivia crept up to her sister's house early Sunday morning, the shadows of willow branches reaching out at her eerily. Even though Mr. Vega's car was already gone from its spot beside the house, she hesitated beside the porch. Somehow it didn't seem right to just walk up in broad daylight and ring the doorbell when she and Ivy were about to snoop around inside. She decided to go around back.

Kneeling beside her sister's bedroom window, she saw Ivy pacing the floor of her room below.

Olivia rapped on the glass with her knuckles, and Ivy jumped, clearly startled. Then she rushed up the stairs and opened the window.

Olivia clambered through onto the basement stair landing.

"You scared me to death!" said Ivy.

"I thought vampires were already dead," Olivia joked.

"Ha-ha.Very funny," Ivy replied.

Two seconds later, Olivia was following Ivy up to Mr.Vega's study. Her sister immediately began rummaging through the enormous mahogany desk, Olivia started with a shelf in the corner filled with tiny drawers. She felt a little awkward about snooping through Mr. Vega's things, but she was certain she'd seen the Lazar symbol yesterday and she needed to know why Mr.Vega had something with that symbol on it.

The first drawer was packed with gray fabric swatches.The second had nothing but little metal plates - none of them with the Lazar symbol on them. The third drawer was filled with minigargoyles.

A half hour later, the sisters still hadn't found the wooden box, and Olivia was starting to get discouraged. There were countless urns, vases, busts, drawers, boxes, and pedestals. The box could be anywhere.

Ivy began circling the room like a caged panther. Suddenly she stopped and slapped her palm against her forehead. "I'm such a fruit bat!" she exclaimed. Then she walked to the front of the desk, where a bunch of files were propped up between two brass gargoyle bookends. She twisted the head of the bookend on the right, and across the room two bookshelves sank back into the wall and slid apart to reveal a dim passageway.

"Cool!" Olivia said, following Ivy eagerly into the shadows. She found herself descending a tightly wound spiral staircase. "Where are we?" she whispered.

"Between the kitchen and the living room," Ivy explained. "This passageway is the only entrance to this room."

The steps ended at the floor of a tiny circular room. Row after row of small, shallow gravestoneshaped holes were carved into the walls. Instead of holding bones, each one held books and scrolls.

"My father's special collection," Ivy announced.

Olivia crept up and peered into one of the hollows.

It was sealed with a pane of glass, and inside she saw a marble tablet carved with mysterious hieroglyphics. Alongside it was stretched an ancient-looking scroll that looked like a blueprint.

"What is all this?" she whispered.

"My dad's old decorating textbooks," answered Ivy from over her shoulder.

Ivy started combing through some books in a hollow across the room, while Olivia gravitated to a nearby stone recess. She pulled down a fat black book with a cracked spine and discovered it was a photograph album.

Olivia's mouth fell open with shock.There was a picture of her as a little girl, wearing a witch's hat and holding a broom! I don't remember ever wearing that for Halloween, she thought. Then she realized that of course she was looking at pictures of Ivy, and she started to giggle.

"Remember when I said next time we'll look at pictures of you drooling and wearing embarrassing clothes?" Olivia reminded Ivy, starting to flip through the album excitedly. "Well, the time has come!"

Ivy winced. "Aren't you supposed to be looking for our box?"

Olivia was about to slide the album back into place, when something caught her eye at the back of the recess. It looked like there was something else there. Something brown. She pulled out another album and reached in curiously.

Olivia's pulse quickened as she felt a wooden edge. Slowly, carefully, she pulled out the box hidden there on its side. Without Olivia having said anything, Ivy appeared beside her.They both looked down at the gilded symbol on the lid - the same symbol that was on their rings.

It's the box I saw yesterday, Olivia thought, her heart pounding. She heard Ivy's breath catch.

Olivia lifted the lid and they stared down at a stack of yellowed papers inside. Ivy lifted out the top sheet by its edges, as if she was scared it would crumble to dust, and turned it over.

"'My love,'" Ivy began reading, but then she stopped. Olivia followed her sister's gaze to the bottom of the page. The letter was signed, Forever yours, Susannah.

"Why would my dad have a letter from our biological mother?" Ivy wondered aloud. Olivia thumbed quickly through the papers and saw that they all seemed to be letters from Susannah.

Underneath the stack was a smaller piece of shiny paper with scalloped edges. On it, in neat script, were the words, Susannah and I on our wedding day.

Slowly, carefully, Olivia picked up the small piece of paper and flipped it over. She could barely believe what she was looking at. It was a picture of her parents.

Susannah wore a long, white lace bridal gown with an elegant scooped neckline, and her face was alight with a mischievous smile that reminded Olivia of Ivy. The picture must have been taken a long time ago, because all the colors in the picture were sort of brownish. Beside her, clutching her hand, stood the tall, broadshouldered groom in a black tuxedo with a skinny black bow tie. He had a huge black mustache and longish hair and was grinning toothily at the camera.

"It's our father," Olivia whispered.

"Let me see!" said Ivy, taking the picture and holding it up in the dim light. Ivy blinked, and Olivia saw something change on her sister's face.

"It's my dad," Ivy whispered.

Olivia nodded automatically: Yes, our biological dad, she thought. Then, all at once, she understood what her sister had really meant. She snatched the picture back.

Behind the unkempt hair and the weird mustache, the grinning groom in the photograph was none other than Charles Vega.

Ivy felt as if her head were a cave suddenly crowded with bats. "My dad didn't adopt me," she heard herself say. "He's my real dad."

"And my real dad," Olivia echoed in a faraway voice.

The two of them stood there, stunned and silent for a long moment.

That's why there was no record of my adoption at the agency, Ivy realized. All her life, she'd wondered what her biological father was like, and now she saw that she'd known the answer all along. She felt her heart swell, and a wave of happiness crashed over her. "My dad is our dad," she said.

There were tears in Olivia's eyes. They began trading the wedding picture back and forth.

"I can't believe he ever had a mustache like that," Ivy marveled.

"He was in hiding," Olivia said with mock offense. "Hey, look," she went on, pointing to the happy couple's clasped hands. "They're wearing rings just like ours!"

Ivy's mouth fell open. "Those aren't like ours," she realized. "Those are ours.We're wearing our parents' wedding rings!" She touched the ring on the chain around her neck, and for the first time she understood why her ring was too big, while Olivia's fit perfectly: Ivy had their father's wedding band, Olivia had their mother's.

"Of course." Olivia sighed like they always should have known.

It must be so hard for my dad to see me wearing it every day, Ivy thought tenderly. She remembered how, after her father had given her the ring for her tenth birthday, he'd become very quiet and distracted for a few days.

"So why didn't he just admit he's my dad?"

Olivia wondered, looking bewildered. "And why did he always tell you you were adopted?"

"My dad always says he doesn't like looking back at the past," Ivy said. She looked again at the picture of their parents and how happy they seemed together. "Maybe it's just too difficult for him. We remind him of our mom." She smiled at Olivia. "Especially you.You're human like she was."

Olivia couldn't stop looking at their parents' wedding picture. My dad's been right here all along, she thought. She felt like a missing piece had been added to her heart, one that she hadn't even known was missing. She remembered the first time she'd met Mr.Vega, when she had been disguised as Ivy and they had been decorating the upstairs ballroom for the All Hallows' Ball together - how sophisticated and stylish and cool he'd seemed. And then she thought of the way he'd offered to vouch for her for her initiation, and how proud he'd looked when she'd passed the tests, and she felt warm inside.

"He'll be home soon," Ivy interrupted her thoughts gently. "We'd better get back upstairs."

Together, the two of them packed the picture and the letters back into the wooden box and returned it to its hiding place. This time, Olivia led the way up the darkened spiral staircase. She wasn't spooked or disoriented at all. Somehow, now, she felt like she was at home.

"Ivy," Olivia began hesitantly as they emerged into the study once more. "Do you mind if we don't tell your dad - I mean, our dad - about our discovery just yet?"

Ivy shook her head. "No, it's fine," she replied, squeezing her sister's hand. "I need some time to get my head around this myself."

A few minutes later, Olivia was lying thoughtfully on the floor of the living room when Ivy let out a long, sad sigh from her place on the couch. "What is it?" Olivia asked, staring at the light gray ceiling.

"I just remembered we're supposed to move to Europe in, like, just over a week," replied Ivy.

Olivia had forgotten, too, and for a moment, she felt like she'd been punched in the gut. It's bad enough that Ivy's leaving, she thought. But now I know I'll be losing my biological father, too!

She took a deep breath and sat upright. "That means," she said calmly, "we have that long to change our dad's mind!"

Slowly, Ivy's face hardened into a look of determination. "You're right. We have to find a way to talk him out of it."

Just then, Olivia heard the sound of a car pulling up outside. The sisters stood up and smiled at each other.

"Our dad's here," Olivia said thoughtfully.The words "our dad" still felt strange to her.

Ivy nodded, and together they headed to the front door to greet him.