Corridor to Nightmareby Dave DuncanPublished by Shadowpaw PressReview by Toby A. Welch  $26.99 ISBN 9781989398937 Why is it that tales that involve portals to other worlds are fascinating? Corridor to Nightmare falls firmly into that category. It starts off with a bang and jumps into a world of sorcerers, gatekeepers, and beasts that are half-man, half-Krendel. To keep things spicy, unexpected nasty people and things also go through the portal. When I crack open a book and find a list of characters before chapter one starts, I appreciate it so much. (I wish more authors did that.) The list is only nine characters long, but I referred to it often as I couldn’t always keep people straight. Such a bonus!  The premise of Corridor to Nightmare is an interesting one. An elderly lady, Agatha, is looking forward to retiring from her job as a village schoolteacher. But that doesn’t happen as she is sent through a portal and lands in another world. What comes next is a roller coaster journey! Agatha’s adventure could’ve been fun and lighthearted – but it wasn’t. (I love books with a tinge of darkness and this one delivers!) When it comes to names, Duncan gets huge kudos for creativity, both…