Against the Stone Beasts

While researching modern art, Andreson enters an ad-hoc gallery and discovers a series of luminous paintings that act as literal portals into a parallel, hostile continuum. Drawn through, he wakes within an alien, translucent city where winged, batlike inhabitants and enormous stone beasts populate a world with reversed physical laws. He struggles with disorienting forces and strange guardians, confronts dangers while resolving to rescue a fellow Earthman glimpsed in the paintings, and adapts his scientific skepticism to survive. The story mixes speculative worldbuilding, visceral action, and a motif of art becoming a doorway to alternate realities.