From the introduction:
In Dimension 19, Prescidia, a pregnant gorgon, was being hunted by Morgan Moriarti when she fled into a cave. In the darkness she saw light and stumbled into a nest of Dimensional Spiders that had created a bridge to our dimension.
The spiders attacked her and she fled through the portal into our dimension. However, the hunter was not far behind her. He too was attacked by the spiders and killed a number of them, but was poisoned in the process.
He was found in an alleyway and taken to the hospital. When he recovered a few days later he escaped and resumed his search for the gorgon.
During his escape, Moriarti assaulted several hospital staff so the police and local authorities are also on the hunt for him. However, he is obsessed with killing the gorgon before she gives birth.