Nightfall
Turns out that although the Darkness is horrible, it is the sight of stars that is most responsible for universal madness. Thousands upon thousands of points of light in the darkness is just too much for the Kalgash psyche.
Cities are indeed set aflame, but not from heavenly fire. Sheerin predicted correctly that people would set fires to drive back the dark. Or simply out of madness.
Many die, many are driven permanately insane, and the rest temporarily insane to varying degrees. The world is in chaos.
Daybreak
All our friends survive nightfall more or less intact (except Athor who is killed during the event). It takes several days for them to return to normalcy.
Sherrin is killed by crazed squatters.
Beenay is reunited with his woman, but their ultimate fate is unknown.
Theremon and Siferra meet up and finally become more than friends. They travel together for awhile before actually joining forces with Folimun of the Apostles as they are the lesser of all evils in the attempt to bring sanity back to the world.