This resource guide provides background for a campaign setting in the San Francisco Bay area of the 1920’s, including urban geography, civic history, and research venues—where San Franciscans go when they break the law, go insane, or die—and sights, sounds, and secrets of a city that make it unique. It is more than a metropolis, it is a living entity whose unique character and changeable nature shape its atmosphere, its institutions, and its leading citizens. It is an excellent location from which to launch campaigns focusing on the Orient, and it possesses abundant research resources and outré locales for scenarios within its extensive boundaries, including the largest, oldest American enclave of Chinese settlers, the world’s most famous haunted house, and two of the most infamous prisons ever erected. Here is a complete a portrait of San Francisco in the 1920’s, with careful attention to the vast body of local folklore and unique opportunities for Mythos investigation.