Doubt (Caroline Auden #1) - C. E. Tobisman Page 0,50

upper body: lat pulldown 15x22; overhead press 5x18; triceps extension 12x15; bicep curl 18x4. Lower body: adduction 3x8; abduction 5x3; lunges 11x13; running 1 mile; squats 20x5.” At the bottom of the note card someone had scrawled a name with a bright-blue Sharpie: FERMAT.

The first thing that struck Caroline was the name. Wasn’t Pierre de Fermat a French mathematician? Why had Franklin written Fermat’s name at the bottom of his workout targets?

Then Caroline focused on Heller’s workout. The numbers of repetitions were strange. Why would anyone do thirteen repetitions of eleven lunges? And fifteen lat pulldowns twenty-two times? None of it made any sense.

Caroline eyed the silent breezeway. Though unused in the winter months, she could imagine the bustle in the sandy-bottomed walkway on hot summer days as club members flocked to the coast. But now, in October, there was no one there. Dr. Heller wouldn’t have used this locker for months at a time. And yet, he’d taped his gymnasium workout targets in an unused summer beach locker.

Maybe he was trying to avoid working out? Or maybe—

Caroline yanked her legal pad from her bag. She flipped through the pages until she found her notes from her conversation with Yvonne. Franklin’s final text message.

Caroline looked down at the message, then back up at the workout targets.

She pulled out her camera and shot a picture of the workout targets.

Then she turned and ran back to her car as fast as she could.

Caroline sat in the Mustang, oblivious to the handful of other cars in the club’s self-park lot. The car’s ancient cigarette lighter powered the laptop balanced on her thigh. Her phone leaned against the windshield, the picture of Franklin Heller’s workout goals displayed on the screen. On the passenger seat, she had angled the yellow legal pad with Franklin’s final text message toward her—the one he had sent to his wife before he’d died on the beach.

She ignored the view out the window. The waves breaking along the deserted beach. The low hills dotted with chaparral. The sunlight glittering on the surface of the ocean. She had eyes only for the clues laid out in front of her.

She studied Dr. Heller’s workout goals. The key was the first word: AIM. If she was right, AIM wasn’t a reference to Franklin’s fitness aims or aspirations. It was an acronym for Access Identity Management. Somewhere in the numbers and letters, there was an encryption key. But where?

Cryptology was as ancient as the Egyptians, but it always followed the same basic rules: the security of the encrypted data depended on the strength of the cipher and the secrecy of the encryption key. Caroline believed she possessed both the cipher and the key in the two strings of letters and numbers that Dr. Heller had written—the workout goals and the text message. But which was the cipher and which was the key?

Whatever the answers were, she needed them fast. The clock next to the odometer said it was 11:03 a.m. That meant she had two hours to file the article. Two hours before the doors of the court closed forever on every SuperSoy victim in the country.

With no easy answer presenting itself, Caroline turned her attention to the only piece of plaintext information she possessed: FERMAT. In bright-blue ink, the mathematician’s name stood out against the typed black workout targets, as if Franklin had wanted Yvonne to focus on it first. But why?

Caroline knew Fermat had been a mathematician. But Dr. Heller was a research scientist, not a mathematician. So then, what was the significance of Fermat to him?

Caroline typed the name “Fermat” into the search pane on her laptop.

Search results spilled onto the page. Pierre de Fermat had been a lawyer and amateur mathematician. As an inventor of integral geometry, he’d invented a technique for finding the centers of gravity of various plane and solid figures.

Was the text message a mathematical equation Yvonne was supposed to solve?

Caroline shook her head. She was overthinking it. There had to be some more obvious answer here. Franklin wouldn’t have made things so hard for his wife to decipher. He’d intended for her to find the article.

Running another search for the mathematician’s name yielded another wave of Google results. Down at the bottom of the second page, something caught Caroline’s eye. Among his many achievements, Fermat had been an amateur cryptographer.

With blood pulsing in her ears, Caroline ran a search for “Fermat’s code.”

The results were exhilarating. Fermat had invented an encryption method where each number corresponded to