LATER THAT EVENING, on one of her last decoding attempts, she used an old postwar retrieval key. She was surprised when the system responded, "For access enter via auditory/visual format." A rare but not unheard-of access path.

Nothing came up with audio. She opened the visual file using NATO documents decoding software. Suddenly her screen filled with black and white. After several seconds, she could clearly make out a photograph. No text appeared, only the photo. She enhanced the pixel quality, enlarging it as much as she dared without distorting the image.

The torn black-and-white snapshot with its smudged white margins showed a cafe scene next to a park full of children. People sat at the sidewalk cafe and stood in small groups. The ones standing were SS. Their backs were turned, but she recognized the lightning bolts on the sides of their collars.

No one looked at the camera. Most of the civilians wore dark shapeless clothes. A candid shot of occupied Paris. Almost half of the snapshot was torn away.

Shaken, she stared at the photo. She'd eaten at that cafe plenty of times, knew many of its habitues. But now she would always think of the Nazis who'd been there before her.

This marked the first time she'd cracked a code revealing a photo without text. How would this documentation be proof for the old woman? But that, she reminded herself, wasn't her job.

After saving the image, Aimee printed a copy. She couldn't help wondering what this woman's reaction would be.

With the photo tucked in her Hermès bag, a flea-market find, she wound a leopard-print scarf around her neck, belted her leather jacket, and locked the office door.

Below her office, she hailed a taxi that skidded to a stop on wet rue du Louvre. Late evening crowds filled the awninged sidewalk cafes. The Seine glittered on her right as the floodlit gray stone of the Pont Neuf flashed by.