Professor Rhinestone was a scientist that operated out of the town of Middleton during the 1940s. For reasons of his own, he developed the criminal identity of the Fog, extorting coal mine owner Mr. Smythe into providing him with special fog coal that allowed him to create massive clouds of fog that made those exposed drowsy and slow-moving. Operating under these clouds of fog, the Fog and his henchmen committed a series of successful factory robberies in the spring of 1942.
The Fog's success came to an end when the Defender and Rusty came to town on shore leave from their civilian identities as members of the United States Army. The pair of heroes learned the source of the fog from Rhinestone himself. Following the Fog's trail, they found him attempting to force Smythe into giving him more coal, strangling the man to death before the Defender and Rusty could stop him.
Having all the coal in the city confiscated, the Fog made a desperate attempt to get it back by attacking the Defender directly. During their fight, the two fall off a pier into the water below and fought underwater. The Defender succeeded in unmasking the Fog and beat him in combat, leaving him to drown in the water.
As the Fog, Rhinestone wore a gas mask that protected him from the effects of his fog.
Rhinestone used "fog coal" a special coal that when burned created a thick pea-soup fog that caused those who inhaled its vapors became sluggish and drowsy.