Reddit mentions of Quadrail (5 Book Series)

In no particular order:

• The Enchanted Forest Chronicles.
  
• The Icarus Hunt.
  
• The Voynich Manuscript.
  
• The Chronicles of Narnia.
  
• Something else that I probably forgot. If I think of anything else, I'll add it.
  
  Most recently, I read the Quadrail series. It was pretty good. It was kind of like Zahn took The Icarus Hunt and expanded it into a full series, rather than a one-off. I think that The Icarus Hunt was better, though.