Where are all the humans? Upon returning from your 100 year voyage in the milky way, you find earth empty and abandoned. Between the decaying remnants of civilization, you discover a terminal for Worldnet, the global network that recorded all human activities. The answer must lie deep in its database. Anxious, you log on. Portal is a computer novel - an attempt of creating and adapting a novel specifically for the computer. The story of the boy Peter Devore, his incredible discovery and the mysterious portal are told by an AI named Homer, who reconstructs it piece by piece out of database fragments. As the plot develops, you acquire accompanying information by accessing eleven additional databases - for example a historical archive, military files or social backgrounds. As you switch between the databases to uncover new details, an extensive sci-fi story unfolds.