Jim Floyd serves as technical assistant to Professor Breckenridge, renting rooms in the upper floor of Bristol's Ten-Kai Tavern and boarding house, run by the young woman known as Miss China. His finances remain perpetually strained as he obsessively funds scientific equipment and experiments, often neglecting rent payments and fueling ongoing friction with his landlady.

He possesses significant engineering aptitude, actively developing Professor Breckenridge's unconventional inventions. This includes creating a gravity disrupter from incomplete designs left by Jim's own father and contributing to the "Space Reflex Telescope," a device projecting messages onto the moon's surface—specifically used to display a birthday greeting for Miss China. His skills also proved vital in building an instantaneous matter transmitter, later adapted into a teleportation system linking duplicate rooms within the tavern.

Jim harbors deep romantic feelings for Miss China, the Ten-Kai's proprietor. His affection drives ambitious gestures, most notably his dedication to the Ether Reflector Mirror project intended to literally give her the moon. Yet, he struggles profoundly to express his emotions directly to her, often seeming tactless or absorbed in his work. This communication barrier creates a mutual, unspoken romantic tension; Miss China is also attracted but perceives his attentions might lie elsewhere, such as with a local florist, sparking moments of jealousy.

His path involves navigating this complex relationship while pursuing increasingly grandiose scientific endeavors with Breckenridge, constantly balancing technical aspirations with personal affections amidst the daily pressures of their shared living space and financial constraints.