"Okay," Joe said uncertainly.

"A pharmacist has 8 liters of a 15 percent solution of acid. How much distilled water must she add to reduce the concentration of acid to 10 percent? " He read. His forehead creased. Then it smoothed out.

"Wait, I think I know this one." Joe grabbed a pen and a piece of paper, scribbling furiously. After a while of full concentration, Tessa could see the furrow on his forehead getting deeper and deeper and at last the pen stopped moving. Joe was stuck.

"Let me see that," Tessa said gently, and Joe reluctantly handed her his paperwork. She scrutinized the steps Joe had taken one by one, feeling a little smile creeping onto her face when she spotted Joe’s mistake at last. Taking Joe’s hand, she pulled Joe closer to her so that he could see. "Come, I’ll show you how it’s done."

"You begin with 8 liters of a 15 percent solution. That means you have 15 percent acid and 85 percent water, right? Let's figure out how many liters of acid and water you have to begin with. 15 percent of 8 is 1.2 liters. So you've got 1.2 liters of acid and 6.8 liters of water-" Joe listened carefully as Tessa explained the steps one by one, oohing and aahing when the logic behind it hit him.

"Now you want to add water until the concentration is down to 10 percent. Note that the amount of acid will remain constant, you're only changing the amount of water. You want 1.2 liters of acid to be 10 percent of the entire quantity. Set up a proportion to find out how much is 100 percent of the quantity," Tessa explained. Joe nodded in comprehension.

"I think I’ve got it now…wait a sec." Joe did some rough calculation on the paper. After a moment he broke into a smile.

"I’ve got it," he said happily. "If I want 1.2 liters of acid to be 10 percent of the entire quantity, I’d need 12 liters of the entire quantity. That means…minus the 1.2 liters of acid, which is also included in the first 8 liters of water…I’ll need another four liters of distilled water."

"That’s right, Joe! See, who says you couldn’t do it? You just have to believe in yourself," Tessa said. Joe smiled at her enthusiasm. He had just known her for a couple of days and already he felt so at ease with her.

"I have a great teacher," Joe said sincerely. They gazed into each other’s eyes for a few seconds. Joe was the first one to turn away.

"I never thought I’d feel this great after solving a Chemistry acid concentration equation! Come on, Tessa, give me more."

Tessa held up another book. "Up for calculus?" Joe groaned.

"Frank?"

"Hi, Callie, it’s me. What’s up?" Frank shifted the phone to his other hand as he held up his wrist. 12.30 p.m. Callie seldom called him this late at night. Good thing he wasn’t sleeping yet.

"Frank, do you remember my friend Mary?" Callie sounded nervous.

"Mary?" Frank racked his brains, trying to come up with a face. "No, I don’t think so. Why?"

"Mary Helen Lee? Kennedy High?" Callie’s voice sounded strangely high-pitched.

"Oh, that Mary!! Yeah, I remember her. Why?" Frank asked again, wondering what could be making Callie this nervous. He remembered the petite redhead from Callie’s birthday party last year. A genius.

"She’s missing." Frank sat up straighter in his bed.

"What do you mean missing?"

"You heard about the mysterious disappearances going on around here?"

"Yeah." Frank had a really bad feeling about what Callie was going to say.

"She went to a friend’s house for a study session and never came back."

"When did it happen?"

"Yesterday," Callie answered worriedly.

"Isn’t it possible that she stopped by a friend’s house somewhere and stayed over for the night?"

"They checked that out, she never showed up in school this morning."

For one second, Frank was dumb-founded. How many does this make now? Five? But he knew he shouldn’t be jumping into conclusions. Then he told Callie that he would try to find out what he anything from his father and that he would get back to her later. His heart was pounding when he hung up.

Joe, he realized with a sinking heart. Joe’s not back yet. Frantically Frank grabbed the phone off his dresser and punched in the number he knew by heart.

Then he heard the sound of a phone ringing. Frank looked up to see Joe at the door flipping out his cell phone. Frank hung up the phone, feeling immensely relieved.

"You’re back."

"Any reason why I shouldn’t be?"

"Don’t get smart with me, kid." But Frank was smiling. Joe was smiling too, meaning he was in a good mood. And he was in his room, meaning Joe was ready to talk. Joe dropped his backpack on the floor and went over to Frank. Frank scooted over to the side to give Joe some space.

"So you ready to talk now?" Frank asked quietly.

"Yeah," Joe answered sheepishly. He kicked off his sneakers and hefted his long legs up onto the bed, making himself comfortable. The study date had left him feeling great. Tessa had taught everything from A to Z about polynomials, derivatives, integration and a few other basic concepts Joe was starting to feel good about himself again.

"Frank, I-" Joe hesitated, lowering his eyes. "I want to apologize for, you know, for everything."

Frank was genuinely puzzled. Joe had done nothing wrong so why was he apologizing? "Apologize? For what?"

Embarrassment flushed Joe’s cheeks but since he was here, he might as well let it all out.

"I haven’t exactly done very well in my exams these past months, and everyone was giving me a hard time about it and well, I guess that kinda blew me up for a while, with my short fuse and all," Joe said quietly.

Frank nodded and waited patiently. He could sense that Joe was keeping a lot more inside him than he was willing to tell.

"I knew I shouldn’t have refused your help, I mean, you’re a good teacher, Frank, and I-" Joe paused and lifted his head, his blue eyes filled with remorse and guilt. "I wasn’t trying to push you away…well, I did, at first."

Joe sighed. "I don’t know why all of a sudden I felt this, this resentment in me toward-" Joe swallowed. "-Toward you."

Frank felt a lump in his throat but he swallowed it down, understanding perfectly that Joe was just telling him how he really felt. He just didn’t expect Joe to be quite so frank about it. With an effort, Frank nodded again, encouraging his brother to go on.

"I am sick of everyone comparing between you and me. I mean, I realize I’m not as smart as you are. Will never be as smart as you are. I am sick of being the stupid one, Frank. Me, the brawn. You, the brain. The thought had never occurred to me before then, but with all this sudden fuss about grades and tests and IQ, I just, I don’t know, snapped, I guess."

"For the first time in my life, I’m jealous of my own brother and I hate it." Joe’s voice had dropped to a mere whisper now. "I hate feeling this way."

"That’s why I went to ask for Tessa’s help instead of yours. I wanted to get away from your shadow."

Frank licked his lips which had suddenly gone dry. "You’ve been keeping this from me for 17 years, Joe?"

Joe’s eyes went wide. "That’s not what I meant-"

"Oh yes, that’s exactly what you meant. Maybe you’ve just realized it, but you’ve actually been feeling this way for 17 years." Frank couldn’t help saying it bitterly. As much as he thought he’d try and understand Joe’s situation, he couldn’t help feeling a little betrayed.

"Frank, I’m sorry-" Joe started to say but Frank stopped him.

"No, Joe, I’m the one who should be sorry. I’ve been blind to your own needs to succeed. All I cared about was myself. I’m sorry for all the times you’ve been hurt by that blindness."

Joe was silent for a few minutes.

"And believe me, I only gave you a hard time about your ailing grades because I care about you. Not because I wanted to rub it in. Not because I cared too much about my reputation as a good student. But because I wanted you to succeed to. And I’ve never EVER thought of you as stupid. You’re smart, Joe. If you weren’t we wouldn’t have solved all those cases. We’re a team. We’re both smart."

"I know, Frank," Joe said with a smile. "I know that now."

"So now do you remember what I told you in the cabin?" Frank asked, smiling himself.

"Every word." Joe patted his brother’s knee. "Thanks, Frank. I’m glad we decided to have this talk."

"Me too. So…no hard feelings?"

"Absolutely none. In fact one of the reasons I came was to tell you tat Tessa had been such a great teacher I think I could beat you in calculus now. Well, the derivatives at least."

"That’s great." Frank’s smile suddenly faltered when he remembered the phone call he had. When Frank finished telling Joe everything about what Callie told him, Joe couldn’t help feeling more than a little worried himself.

"So you wanna check it out?" Joe asked, frowning.

Frank shrugged. "I’m thinking of trying to find out for myself. You game?"

"Absolutely." Joe’s mind was racing. What could be the cause of all these mysterious disappearances? And what do all these missing teenagers have in common? Though the questions kept badgering him, Joe felt too tired to dwell on them any further. He said goodnight to Frank and went to his room. Minutes later, he was fast asleep.

"If you can give me the answer to this one, I’ll let you live. Would you like that?"

He nodded through his gag, his vision too blurry with tears of agony to really focus on his captor hovering over him. He could feel the spiky, sharp nails digging into the flesh of his back, his arms, his legs…He felt as if he was lying on a bed of scorpions.

"Since you’re so smart, I’m sure you can answer this in no time." He recoiled when he suddenly felt the hot, fetid breaths against his face. Somebody please help me, he begged silently. Oh God, please…

His head jerked back suddenly when his kidnapper grabbed his hair and pulled it back, causing a new burst of pain that shot through his skull. "If I drive a hundred nails in you, and I add a hundred more, how many nails would there be inside you now?"

He choked through his gag. He was terrified.

"Answer me!!!! Do you want to live or not!!!!" He nodded his head frantically, his eyes wide with fear and pain.

"Good boy. Now what’s the answer?" the question came out more like a purr.

He tried to answer but he couldn’t. The gag was muffling him. "Mmph…mmmhph…"

"What’s that? I can’t hear you," his captor said, smiling. Picking up a long sharp nail off the bed, he tested the sharpness of the tip against his thumb. He gloated as the single drop of blood appeared.