He dragged a low-resolution photo into the window. It was a picture of his grandfather from the 1940s, a grainy, sepia-toned shot taken in front of a mysterious building in Berlin. The face was a smudge of pixels.

Elias felt a cold draft in his apartment. He looked at the bottom of the software window. A new prompt had appeared, glowing in a dull, sickly green:

He zoomed in further, his heart hammering against his ribs. In the reflection of the reflection, he saw a desk. On that desk was a computer monitor. And on that monitor was a download bar, stuck at 99%, for a file named sigma4pc_com.rar .

The file wasn't a tool. It was a bridge. And something had just crossed over.