"To Die in Italbar" (at least the copy I picked up from the library) actually contains two books by Roger Zelazny. "To Die in Italbar" and "A Dark Traveling." I'm not really sure why they were paired together because to me they seemed very different, but I enjoyed both of them! Just for different reasons.
"To Die in Italbar" tells the story of a man named Mr. H who is rather different. He goes through cycles where he is highly contagious to those around him, and cycles where he can heal the people around him. He doesn't really know why, and he doesn't really care.
Until Mr H. snaps that is. Well, he didn't really care at that point why he had these abilities, all he cared about was hurting those around him. He was bitter and angry, and it was time to start a plaque that would rock the galaxy. Now there are multiple people trying to track down Mr. H, all for different reasons.
"A Dark Traveling" seems to have been written for a slightly younger audience. It reads much quicker and with less thought, but it's still very entertaining! It's the story of a young man, mostly normal, unless you think his sister being a witch, his uncle being a werewolf, and the fact that he seems to have werewolf tendencies to be abnormal that is. James's family are like guardians. The help to monitor these "bands" that are basically parallel realities.
James's father has been attacked and sent to a "dark band," one of the realities that is usually avoided because of the danger they represent. Now it's up to James, his witchy sister, and their exchange student from a different band to find out what's going on and put it all right! Along the way they all learn more about what there abilities are, and some secrets about the family are revealed.
Both books put forth some really interesting ways of looking at reality and are well worth the read!